Overclocking: HowTo

[Highland3r]

Basic Overclocking Guide.

****NOTE**** If you are in any way uncertain about overclocking don't do it. Make sure you feel confident in what you are doing; this will avoid you making mistakes and risking hardware. If you have any questions ask someone for advice. *****

Firstly, despite what people might tell you, overclocking isn't that hard to do, anyone can overclock their CPU, memory or graphics card. That's the easy bit. The hard part is knowing how far you can push a certain piece of hardware, and getting everything to run as fast as it can at the same time.

These guides are by no means "gospel" each person overclocks in a different way. I've tried to make this guide easy to follow, and provide the basics on overclocking. If anyone has any suggestions, or thinks something should be changed feel free to suggest it.

First up is a beginner’s guide to overclocking, will add a more advanced guide if people want it, along with requests if anyone has them. Also note, an overclock is 100% guaranteed, some systems will overclock better than others. Overclocks with the same model CPU can vary from machine to machine; it's quite often luck of the draw.

So, where to begin....

Make sure you have decent cooling, not just on the piece of hardware you're overclocking, but for the case too.
In theory, the better you can cool things, the further you can overclock. This isn't always the case, but 9 times out of 10, a cooling upgrade will improve an overclock.

Ensure your PSU is up to the job. A decent brand (i.e. Antec, Enermax, Tagan, OCZ, PCP&C, Zippy) supply will often beat a much higher powered generic supply. It’s worth spending a decent amount on a PSU. Tagan offer great value for money, high powered quiet supplies.

Cooling, be this air, water or phase; ensure a good contact between the cooler and the heat source. Arctic Silver 3/5 or ceramique are probably your best bet, and should be easy to get hold of. A small tube should do 20 CPU’s or a similar number of graphics cards.

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Now, onto the overclocking.

Get yourself a copy of "memtest86" whether this be on CD, floppy, or selected from the bios for you DFI users, it doesn’t matter. Ensure optical drives are set as the main boot drives.
You will also need a copy of ”Prime 95” or “Stress Prime 2004” All of the above can be found via a quick google.

Boot to the motherboards bios, and familiarise yourself with settings. Also locate the "clear cmos" jumper on your motherboard; this should be located near the cmos battery.


For those people with multiplier unlocked CPU's (A64 users **excluding Semprons**, Athlon Mobile (Barton and thoroughbred) and Athlon XP pre week 39 and Intel "ES" users) drop the multiplier now as far as you can. For those of you with multiplier locked CPU's things become a little harder, we'll deal with this later. For now, read on but don't attempt the following.

With the multiplier dropped, the CPU is removed from the equation when finding the ram’s top speed.


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**A64 users note** You also need to be aware of the following when overclocking. A64 boards use a "hyper transport link" (HTT) rather than a traditional "FSB" (Front Side Bus) for this guide however it will be referred to as FSB to avoid confusion. An "LDT" or Hyper transport multiplier are used to control the HTT speed based on the "FSB". As a general rule this should be kept at or below 1000 MHz. At the default 200 fsb, the multiplier is 5, giving a HTT speed of 5*200 = 1000MHz. At 250 fsb, using a 5* LDT multiplier the resulting speed is 1250 MHz, which is too high. So, between 200 and 250 "fsb" use a 4* multiplier. Between 250 and 300 use 3* and so on. Try and keep the "fsb"*LDT less than 1000.
Also note, do NOT use 0.5 multipliers when overclocking an A64 where possible. These introduce a memory divider as the boards cannot derive a memory speed based on the 0.5 multi's, and instead rounds up to the nearest whole multiplier.
For example, 10* multiplier at 200 fsb:
CPU speed = 200*10 = 2GHz, memory speed = 2 GHz (2000 MHz) / 10 = 200 MHz.
However using 10.5* multiplier, the memory is divided by the next whole multiplier so....
CPU speed = 200*10.5 = 2.1GHz, memory speed = 2.1 GHz (2100 MHz) / 11 = 191 MHz.

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Overclocking the memory

Being by finding your memories rated speeds at stock FSB and Set these in bios.
Now begin increasing the FSB by 5 MHz at a time. After each, loop memtest test 5 for 5 loops, and give ALL tests a single loop. This will stress the memory, with errors displayed if it's unstable.
Once a loop has passed, increase the FSB by another 5 MHz. Continue this until you get errors shown within memtest, or the PC refuses to boot. If the PC won't boot, move the cmos clear jumper to the clear position **with the pc turned off** wait 30 seconds, move back to default and reboot, remembering to re-set bios settings as before.
Drop back 5 MHz and run test 5 for 30 minutes, with 3 full loops, this should take ~ 45 minutes in total depending upon the amount of system memory installed.
If this passes, then the memory is fairly stable. To test stability further, boot into windows, and run "prime95" OR "Stress Prime 2004" for 6+ hours. If this passes, then the systems stable. Increase the CPU's multiplier to bring the CPU back to as close to stock speed as you can. This should leave you with stable settings, CPU at stock, memory overclocked.

**Tip*** When running Prime/SP2004 Choose "blend" then the "custom" option. From here, drop the memory usage to ~ 75% of your total system memory. This should ensure the system is loaded 100% while running the test. Those people running dual cored CPU’s, 2 instances of Prime or SP2004 can be run, one assigned to each of the cores ***TIP***


There should be more headroom in the memory once these stability tests have passed. Memory latencies can be eased to increase the overclockability. This however is not quite as clear cut as it sounds. Reducing the memory timings increases the number of clock cycles taken to perform a certain action. For example a memory read may have a latency of 2 cycles set. Dropping this to 4 cycles may allow the memory to overclock further however; a much higher bus speed is required to overcome the added 2 cycle latency. So, as a general rule, don't relax your timings to less than cl 3, trcd 3, and trp 3 (unless defaults are looser than this i.e. 3, 4, 4 at default)
Voltage increases are also available to help push an overclock further, however certain memory types require varying voltage levels to perform to their full potential. Advanced memory overclocking will be looked at in further detail in a later guide.

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For users with no multi control: Things get a little complex for you guys, as there’s no way to drop the CPU speed, so both memory and CPU have to be overclocked at the same time. You *could* run a memory divider at this point to run the memory faster than the FSB speed. There are however certain issues with doing this. Firstly not all motherboards use the same dividers; secondly the dividers available can depend on the CPU, memory and bus speed of your system. So, the simplest way (for this guide) is to overclock both the CPU and memory at the same time. So, here's how it’s done. As before, set the memory to its default timings, CPU at stock etc and ensure "memtest86" disc/floppy is inserted and the bootable disc.
Follow the guide above for memory overclocking, increasing the FSB 5 MHz at a time, running memtest after each. **This time also run test 8 along side 5. This tests the CPU a little more as well as the memory**

Take note of the steps below in the For ALL users section.

At the same time, be aware of an increasing CPU speed. If a certain FSB fails to boot, or fails memtest try adding a little more CPU vcore to help stabilise things, and run again. If this still fails, then the limit may have been reached.

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[Highland3r]

Overclocking the CPU

Now that the maximum of your memory has been found its time to find the max of your CPU.
The basic principle of this is to increase the CPU speed until the system is no longer stable. Start off by setting your FSB and multiplier back to stock. Leaving memory settings as they were from the previous stage

For those people with fully multiplier unlocked chips (i.e. AMD FX, Mobile Athlon XP's or Intel ES chips) things are a little easier. Instead of increasing the FSB (as noted below) simply increase the multiplier to find the CPU’s maximum speed. The other instructions (voltage and stability testing) still apply to you guys though! FSB increases can be used to fine tune an overclock, this will be covered by the advanced guide.

For those with multipliers available down only, (i.e. AMD64 users, Pentium M owners) Set the multiplier to stock, and bump the fsb 5 MHz at a time. Until you (if you reach) the FSB previously found when testing the memory.

For ALL users: After each increase (either FSB or multiplier) boot to memtest, and loop test 5 for 4 loops. This is to ensure the CPU and system have some basic stability. To test this further, boot to windows and run Super Pi's 1M test. If this passes, reboot and up by another 5mhz. Repeat until either one of the tests fails, or the system refuses to boot. If the PC won't boot, move the cmos clear jumper to the clear position **with the pc turned off** wait 30 seconds, move back to default and reboot, remembering to re-set bios settings as before.
If one of the tests fails, increase the CPU's vcore by 1 notch (this is usually 0.05v) and repeat the FSB or multi increase. For those people using multi adjustment, a larger increase may be required as the frequency jumps are a little higher.
As a general rule, don't increase the vcore more than 10% of stock (i.e. 1.4 stock volts would give a max of ~ 1.55) load temperatures should be kept below 55 degree's.

Once the maximum vcore has been reached, or you do not wish to overclock the CPU any more, loop Prime or Stress Prime 2004 for another 6+ hours to confirm the CPU is stable. If a failure occurs during this time, drop 10mh from the FSB, or drop to a lower multiplier. Re-test again and drop speeds further if required. If load temperatures are low (i.e. under 55 degree's) more vcore can be used if necessary.
**** Note **** 6 hours does not prove system stability, I’ve seen prime fail after 22 hours on occasions. It is however unlikely a system would be loaded for this long in a real world situation, so you should be ok. ****

For those users running fixed multiplier systems, the overclocking is done. Sit back and enjoy the new speed!

For those users with multiplier control however there’s a little more work to be done.
Now is the time comes to combine the memory and CPU overclock. Since the maximum memory and CPU speeds have been found separately these can be "mixed" together to give a resulting CPU and memory overclock.

Using your maximum **stable** memory clock as a base, find a multiplier which will give you the closest maximum **stable** CPU speed. It's better to go a little lower on one of the 2 if necessary. You may also find that both loose a few MHz in maximum stable overclocks, this is normal.

Once set, again loop memtest for 45-60 minutes before booting into windows.
Run Prime95 or Stress Prime 2004 for a minimum of 6 hours. If this passes then the system should be stable for 24/7 use (note the comments above however). If not, drop the FSB a few MHz (this will reduce both memory and CPU speeds) and re-test. Continue dropping until the system is stable.

If you experience instability back off your overclock until these stop.

Once overclocked, keep an eye on your temperatures. If the CPU goes above ~ 55 when under heavy load then consider a cooling upgrade, or dropping the overclock. Also note, temperatures will vary with the time of the year. You may find the overclock may have to be reduced over the summer to keep things running stable.

Now that you're overclocked, sit back and enjoy the extra speed increase from your system...

Coming soon, the advanced guide, including fine tuning the overclock, graphics card overclocking will also be covered.

[Highland3r]

For this guide, we'll be looking at graphics card overclocking. Graphics cards offer 2 areas for performance improvement, memory and the GPU (Graphics Processing Unit). As with Overclocking a CPU or ram, the general rule is that, the higher the clockspeed the higher the FPS.

However (you knew that was coming didn’t you!!) its not quite as clear cut as 500mhz beats 300. Within a modern GPU there are shaders, pixel and vertex (there may be others, but lets keep this simple for now). These carry out shading operations on the displayed image at the pixel level. Adding lighting, shading and other fancy effects.
Now, how does this affect speed you may ask. Well it’s simple. A card with 1 pixel and 1 vertex shader can perform 1 pixel operation and 1 vertex operation each cycle. So if the core were operating at 200mhz, (200,000 cycles per second) in 1 second, 200,000 pixel and vertex operations per second.
So if a modern card had say 16 pixel shaders and 8 vertex shaders, what does that equate to?

Well with a core speed again of 200 MHz. 16 * 200,000 is 3,200,000 pixel operations per second, and 1,600,000 vertex operations.

So, as you see there are many factors which might affect the "speed" of a graphics card rather than just pure MHz.

**Task: If you get bored try and work out the theoretical clockspeed you'd need from a 16*8 card to match a 1*1 ****

**Note my knowledge on this subject isn't massively hot, so if any of the above is utter tosh, please drop me a line**


So, now we're all confused, let’s get onto the good stuff - overclocking!

As with CPU and memory overclocking, cooling is key. Stock sinks are often good for a few MHz, but in most cases its worth swapping them for something a little beefier. Arctic Cooling's VGA silencer series offers a little boost in cooling, while keeping noise levels down. However the increase in cooling isn’t huge. Zalmans VF-700 series are equally quiet when run on 7v, and provide a little more on the cooling front, especially when run at 12v. Other options include modded CPU sinks, A64 and Intel stock sinks are a cheap source of these, and work well with updated fans. Water (obviously) is better than air cooling, with a wide range of blocks to suit most cards. Phase and Dry Ice/LN2 cooling round up the more extreme side of things.

Once the coolings sorted, its time to overclock!

Grab yourself a copy of your preferred graphics overclocking utility - Rivatuner, ATI-tool and powerstrip are 3 which come to mind.

You'll also need a copy of 3dmark01 and 03, as well as your favourite computer game.

Once installed, navigate your way to the overclocking options (note in rivatuner, choose "low level system" rather than the software option. This is the top of the 2 drop down boxes.)



ATI tool has a built in "max overclock finder" however this can be a little flaky, so we'll cover the "old fashioned" method first. If you want to use it by all means do so, but follow the stability guidelines below once ATI tool has been run to double check.

As with overclocking before, first we'll deal with the memory side of things.
This is made a little easier by first checking what the memory on your graphics card is actually rated too.
Often, the memory speed set is lower than the stock speed of the memory modules installed. So, here’s how you work out the rated speed of your graphics cards memory:
Take a close look at the ram chips on the card, there’s loads of writing present. Look for the line with lots of numbers and letters on it. At the end a number. This number is the NS rating of the memory chip.
i.e., if the line ends 30, the NS rating is 3.0. Likewise if it ends 28 then the NS rating is 2.8. Simple eh?!



**Note** You may find that the NS rating isn't here, ram chips differ. Just look for numbers at the end of a line, or on a separate line. Sometimes these include a decimal point, sometimes they don't. It's hard to be precise with this due to differing locations for various ram chips, if you aren't sure which number to use post everything written on the chip, and someone will work it out for you. ****

Now, armed with your NS rating (if you don't have it, not to worry) divide 1 by it. Then multiply this by 1000.
So, for a 2,2ns chip the calculation would be... : 1/2.2 = 0.454, 0.454 * 1000 = 454.5mhz.
The stock speed for 2.2ns ram is 454.5 MHz or 909 MHz DDR (double data rate)

This then means in theory cards with 2.2ns ram should clock to a minimum of around 454/909 MHz memory wise.

So with this in mind, begin upping the memory frequency. If you know the rated speed, you can up in 15-20 MHz jumps to begin with. After each jump, run the "nature" test of 3dmark 2001 for 5-10 loops, and give a couple of runs through 3dmark 2003.
If this passes, notch up another 15-20 MHz and try again.
Continue this until you notice visual artifacts in the tests. This may appear as dots, or as large blocks of grey or other random colours. If you see this, hit escape to exit the test straight away. Drop the memory speed 15-20 MHz and try again. Continue dropping until the tests run with no artifacts.

For those users who are unaware of their rated memory speed, you can also use the same jumps, but do so for only ~ 100mhz increase over the cards stock speeds (if you are able too without artifacts). From then on increase in 5-10 MHz intervals, testing after each.

**Warning** If you see visual artifacts exit the game test ASAP. If these remain once you are faced with the desktop, reboot the machine as quickly as possible. While permanent damage shouldn't occur, it’s better to be safe than sorry ***

Once you've reached a stable point, where the next 15/20 or 5mhz jump results in artifacts, drop back a further 10mhz and loop 3dmark 2001 a few times, doing the same with 03. As before if any visual anomalies are noted reduce the memory speed.
If these pass, sit back and play your favourite game for a good 3+ hour session, running 3dmark 2003 when you finish. This should stress the graphics memory enough to ensure its stable.

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Now that you've found a stable memory speed its time to move onto the GPU
The overclockability of the GPU varies greatly from card to card. Some overclocking like banshee's, others won't make 50 MHz. Unlike ram there’s no way to get an initial idea how far you can take the core speed.

So, to start drop the ram speed back to default, check the coolers fitted ok and fire up your overclocking tool again.
Again, increase the speed by 10-15 MHz at a time, running run the "nature" test of 3dmark 2001 for 5-10 loops, and give AT LEAST 2 runs through 3dmark 2003. This time we're looking for small white or coloured dots on screen. These will most likely appear after a short period of time, as the core heats up.
For those users with temperature readings available check the temperature readings after each loop. For those using Rivatuner, the readings can be found on the 2nd to right option in the same section as the clock adjustment option.
If the tests pass, increase by another 10-15 MHz and repeat.

***Note*** You may find the screen locks up (i.e. the image doesn’t move at all) if this occurs, press escape a few times to exit 3dmark, this may take a few seconds to respond. If this fails, turn off at the power switch ****

Once the tests fail (either with a lockup or visual artifacts) keep dropping the clocks until the tests run clean. If the card has locked up, drop 20-30 MHz and run an extended test.

Once "stable" clocks have been reached, run an extended test (as above for memory) and drop clocks as necessary.

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[Highland3r]

Now that a max memory and GPU speed have been found as with system overclocking its time to pair them together.
Chances are especially when GFX overclocking running both the memory and GPU at their maximum overclock will result in artifacts of some sort, so bare this in mind when setting the frequencies. Try 5-10 MHz lower on both to start with, you can always work up if things run stably.
So, again set the clocks, and run the same stability tests as mentioned above, as well as your favourite game for a few hours. If everything’s crisp and artifact free then your good to go.
As before though, if visual artifacts do appear, drop the clock speeds to stop them occurring.

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Additional info.

-= ATI Tool =-
Use it by all means, but be a little careful, it *can* continue to increase the clockspeeds to unsafe levels, so keep an eye on it. Likewise it can recommend clocks much lower than the cards capable of. Run the same stability tests as above to confirm its recommendations once you've run just to be sure.

-= Dangers =- If the GPU or memory is overclocked too far, and left for a long period of time artifacting then permanent damage can occur. If you notice artifacts drop the clocks. It’s better to be safe than sorry.

Keep an eye on the produced 3dmark scores, if you notice they start to drop as you overclock the card higher, it’s an indication you've gone a little too far. Drop the clocks until the score starts to pick up a little.

As we mentioned at the start of the guide, the number of pipelines a card has can affect performance. A nice guide was written over at bit-tech.net detailing how, on certain cards some of the pipelines can be unlocked.
Certain GPU's are simply downgraded to a lower model if the batch they come from is deemed faulty. The extra pipelines are simply disabled, and in some cards these can be re-enabled to give a boost in performance

Softmodding Guide

This won't work for all cards, and even for the cards which do have unlockable pipes, not all will be successful.

[Highland3r]

Requests #1

What do YOU want to see in this section! Post and we'll see what we can do!

Aphex asked: i have heard rumours that with some a64 more voltage isn't necessarily good for overclocking which is one of the founding creeds of overclocking really... is this true??

Yes, this is true and its not limited to A64's and for that matter CPU's.
The major enemy when overclocking is heat. More voltage = more heat, and more heat = a lower overclock. Thats the simple answer lol! This goes for CPU's, memory, gfx cards the lot...
This is where the "art" to overclocking comes in... It's not just about pumping up the volts and seeing how far you're FX55 can go on 2v. Almost EVERY component you can adjust the voltage on will have a "sweet spot" which will give a good overclock, without going insane with the voltages.
A real world example now, my old 730M "dothan" feed it 1.6v and it'll do around 2.45-2.5ghz. Now, drop that to 1.425v, and it'll still do the same 2.5ghz stable. Now by the general law of more volts = more speed this kinda bucks the trend. Its the same for many cpu's though, after a certain stage increased voltage yields nothing. Whereas the same CPU may scale much better with voltage. Its down to the individual characteristics of the silicon in each chip.

On a similar line, memory. There are 2 very conflicting memory types, which are well known to most. TCCD and the Winbond BH series. Its kinda a tortoise and the hair, BH loves tight timings (in fact its rare for most of the winbond series chips to boot at any cas latency higher than 3) whereas TCCD (and TCC5 its little brother) run best at 2.5,3,3,x or looser timings.
TCCD will run 2,2,2,x timings typically to around 220 fsb max, BHx series ram should match this too. Above that, and things change. Dropping to 2.5,3,3,x timings TCCD will continue on to around 250-300 fsb with no voltage bump, and maybe minor tweaks to alpha timings. BHx series on the other hand will hold its tight timings to around 260 (and often higher with the good samples). The major difference is however TCCD will reach its heady heights with under 2.9v. BHx will need closer to 3.9v to achieve its resutling FSB.
As to which is better, it depends. Performance wise its probably similar in real world tests, 260 2,2,2,x and 300 2.5,3,3,3x theres not really much in it. Realistically, the TCCD will run MUCH cooler and the lower voltage will make it MUCH more manageable. This is why its become the ram to have lately, its huge range, low FSB with tight timings, and high fsb with slightly relaxed makes it ideal for all, coupled with the fact it runs REALLY well on A64 platforms...

This takes us onto Aphex's second point but i think a run down of which memories [bh-5, tccd etc etc] like what voltages timings etc in one place would be really good imo...

So here goes!
(start with low latency)
Winbond series memory. This includes: BH5 and 6, CH5 and 6 and newer UTT.
Voltage range: 2.9-3.8v (though CHx shouldnt be run above ~ 3.4 due to the process its made on. Newer CH based UTT is fine to 3.8) **requires active cooling**
FSB range: 200 -> ~ 260-280
Timings: 1.5/2,2,2,5 these should be ok to ~ 260+
Notes: Winbond chips (especially BH and the newer UTT) scale with voltage, as you feed them more the go further, though as noted above, there is a celiing. Ideal for low latency, high FSB.
Found in: Wide variety of chips, often value ram. OCZ VX series, Mushkin's Blue and Redline series, Twinmos Speed Premium, Geil one,

Micron (found in Ballistix and OCZ EB)
Voltage range: 2.7-3.1v (require active cooling, these run warm)
FSB range: 200 - 300+
Timings: 2,2,2,x up to around 250 fsb (for 512/256 mb sticks) and 3,4,4,x or tighter to 300 or more FSB
Notes: Tend to prefer cas3 or 2.5 over 2, but should hold trcd and/or trp 2 to 250. Drop cas first. Tollerent of voltage up to ~ 3.1v. Under-rated ram, tends to run tighter timings better than TCCD, at voltages lower than winbond chips require, while still achieving a good top end FSB with looser timings.
Found in: Crucial Ballistix, OCZ's EB series.

Samsung: TCCD/TCC5
Voltage range: 2.5 - 2.9v
FSB: 200 -> 320
Timings: 2,2,2,x to ~ 220, 2.5,3,3,x to ~ 270, 2.5/3,4,4,x to ~ 320
Notes: Run better with low voltage and 2.5,3,3,x or looser timings. "Good" TCCD will hit 300 or more. TCC5 is a newer revision of TCCD, tends not to be quite as fast, but many chips are.
Found in: OCZ EL 3200 (rev2 only), Corsair XL series, Gskill LA/LB/LC/LD/LE/LF, Patriot, PQI Turbo.
As a general rule, if the memory offers 2,2,2,x at 200 and / or 2.5,4,4, or 3,3 at 250 then its probably TCCD or TCC5. (There are more modules with TCCD on, these are the most common)

Hynix: All types
Voltage range 2.5-3v
FSB: 200 - 300
Timings: 2.5,3,3,3x or worse at 200 and above
Notes: Loose timings suit Intel boards, these are a good choice for P4 based systems, as Intel tend not to be affected as much by looser timings.
Found in: Various modules, OCZ Performance (4200EL for example) Adata Viesta (DDR500)

[Highland3r]

This guide provides some tips and tweaks for getting the most out of your shiny new core2 system.

Overclocking a Core2 is similar to clocking an A64, as the chips come with downward selectable multipliers.

There are specifics to both 965 and 975 boards which overclockers should be aware of. Both boards have their advantages and disadvantages, being aware of these could help improve your overclock.
Users of NVIDIA boards would like your thoughts and feedback as much of what’s said below may not be applicable to you guys!

So, let’s start off with the 965 chipset.
- Due to the lack of "down clock" memory dividers, users only have options to run ram at a 1:1 ratio or higher. This isn't a huge issue; it just means if you're board runs out of FSB you can’t push your CPU any further.
Unless you're running an E6300 this shouldn't be a problem for most users as CPU speed will be the limiting factor well before motherboards start to max.
- Some users may experience an FSB wall at between 350 and 380 FSB. Try booting at 401 FSB or higher and see if that helps. It seems, at 400 FSB the 965 boards drop to a higher chipset strap which loosens the chipsets internal timings. You do however need to be aware that you'll need around 430-440 FSB with the same memory timings to compensate for the looser chipset timings. You may find its worth running close to the "changeover" point to achieve the best performance (390-399 FSB)

975 boards -
- These boards *tend* to max at around 450 FSB. vMods will probably be required to push higher. The vMCH option in bios should help you out here however, this is the chipset voltage. Wouldn't run above ~ 1.7 for long periods of time and make sure you add a fan over the chipset to keep things cool. (1.8v maybe suitable with upgraded cooling, however this isn’t recommended)
- 975 chipset offers down clock dividers for the ram (i.e. ram can be run slower than FSB speed). This is useful if your ram runs out of headroom and there’s still scope to push the FSB further


Both 965 and 975 boards (Please note, this info is still under investigation by Tony and Freecableguy at The Tech Repository below info was taken from a thread there.)

It has been found that the CPU multiplier comes into play when the Northbridge speed is calculated.
So, for example stock E6600 has a multiplier of 9.
The Northbridge clock = (stock multi/set multi) * FSB

In the case of a stock E6600 running at 500FSB, the NB speed = 500 MHz (9/9)*500

However, drop the mutli to 6 and we see a different story (9/6)*500 = 750 MHz.

So, what does this mean for the overclocker? Well, it means you need to be careful when using non-default multipliers on your CPU. Dropping the multi may well drop your CPU speed but you need to be aware it will probably be increasing your Northbridge speed.
Care especially needs to be taken when memory testing where often using a low CPU multiplier is used to find the maximum memory speed. In such situations, using up clock memory dividers offers a solution which alleviates this problem.

However this feature also has its uses. It does allow you to fathom out the maximum FSB your motherboard should be capable off (assuming other components do not limit the FSB) Dropping the multi will allow you to test the limits of your motherboard.

As always any mistakes/comments/additions please post them.

Cheers

[Leeum]

Awesome work mate

Stickied.

[coolmiester]

Well i know what i'm doing next weekend

That guides an absolute master piece

Great job Highland3r

[shizen]

Wow, great guide highland3r. But one question, can i overclock the cpu with out overclocking the memory?