Just a simple step-by-step guide for new overclockers to easily overclock (OC) their C2D/C2Q.

Note : Computers/overclocking is my hobby. Heck, I'm not even in the computer field. I'm just an average overclocker. Forgive me if there are incorrect facts....

Any recommendations/comments/incorrect facts, pls inform me through pm.

Index:
1) Introduction
2) Part 1 - BIOS settings
3) Part 2 - Assessing stability of your first OC
4) Part 3 - Higher OC
5) Part 4 - Checking for stability of your OC
6) Part 5 - What is safe vcore and core temperature
7) Part 6 - Should I reduce the CPU multiplier?
8) Part 7 - RAM settings after OC
9) Part 8 - What is vdroop/vdrop?
10) Part 9 - What is FSB wall?
11) Part 10 - What is FSB strap?
12) Part 11 - References

-------------- Introduction ------------------------------

Remember:
Do this at your own risk
Overclocking can damage ANYTHING & EVERYTHING on your rig and may reduce the lifespan of certain parts
Make sure you have a good:
- PSU
- CPU HSF (stock HSF is not recommended)
There are many other ways to OC your rig, this is only one of many ways

Softwares that you need: (You should google for the latest version)
1) CPUz (Get it here)
2) Prime95 v25.5 (Get it here)
3) Core temp 0.96 (Get it here)
4) Easytune5 (that comes with your mobo) - for other mobo, you can use their software.....

--- You need easytune5 to increase your FSB for overclocking. If your mobo doesn't come with any software to increase the FSB, you can use the "SetFSB" program. (Download here : Get it here) However, you need to:
--- know your clock generator type
--- read the instructions carefully as they did mention that it is NOT for beginners.....
Important : For Prime95, you need to enable "Round off checking" in Advance menu. If not, you won't be notified of any errors that occur! (But you can still see the errors in the windows)



Hardware used in this guide:
C2D E6750 (8 x 333 = 2.66Ghz)
- CPU multiplier : 8x
- Bus speed ----: 333mhz
- Stock voltage : 1.35v (may vary)

C2Q Q6600 G0 stepping (9 x 266mhz = 2.4 Ghz)
- CPU multiplier : 9x
- Bus speed ----: 266mhz
- Stock voltage : 1.25v (may vary)

E2160 (9 x 200mhz = 1.8 Ghz) - I don't have this proc, just did some research on the net
- CPU multiplier : 9x
- Bus speed ----: 200mhz
- Stock voltage : 1.225-1.325v (may vary)

C2D E8400 (9 x 333 = 3.0Ghz) - I don't have this proc, just did some research on the net
- CPU multiplier : 9x
- Bus speed ----: 333mhz
- Stock voltage : 1.15-1.225v (may vary)

Gigabyte P35-DS3 mobo

Don't get confused as I'm including both CPUs in the guide.....
Should be able to use this guide for other C2D/C2Q
Why I used these parts as examples? Because I only have these parts!!! You can sponsor me other parts then I can create a guide for that particular part

Before you start:
Know how to reset your motherboard's BIOS if anything goes wrong (usually you need to connect a jumper on the mobo)
Know what is CPU multiplier, bus speed, fsb, vcore, vdimm

------------ Part 1 : BIOS settings ---------------------

Start by going into BIOS - BIOS setting may vary with different mobo
For GA-P35-DS3, once your in the BIOS main page, press "Ctrl + F1".
- This will enable extra options in the M.I.T page
- For new bioses, you don't have to do this

Advanced BIOS features:
CPU Enhanced Halt (C1E) - disabled (for stability)
CPU EIST function - disabled (for stability)
Virtualization Technology - disabled
CPU Thermal Monitor 2 (TM2) - enabled (for safety purposes)

MB Intelligent Tweaker (M.I.T) features - make sure you have pressed the "Ctrl + F1" before entering this page

CPU Clock Ratio - No need to change (to make things easier)
- 8x for E6750
- 9x for Q6600
- 9x for E2160
- 9x for E8400
- you can put a lower multiplier with a higher bus speed

CPU Host Clock Control - Enabled (so that you can set the frequency)

CPU Host Frequency (mhz) - this is where you overclock!!! Let's start with a small OC first
- E6750 - 390mhz (so 380mhz x 8x = 3040mhz)
- Q6600 - 320mhz (so 320mhz x 9x = 2880mhz)
- E2160 - 280mhz (so 280mhz x 9x = 2520mhz)
- E8400 - 400mhz (so 400mhz x 9x = 3600mhz)

PCI Express frequency (Mhz) - 100mhz (prefereble not to put auto)

CIA2 - disabled

System memory multiplier (SPD) - 2.0 (lowest multipler)
- to downclock the ram to the lowest settings (so that it doesn't interfere with the CPU overclocking)
Memory timings (set loose timings of 5-5-5-15)
- CL 5
- Ras to Cas Read delay 5
- tRP 5
- tRAS 15

System voltage control (Manual) - so that you can set your voltages
DDR2 overvoltage control ---- Normal
PCIE overvoltage control ----- Normal
FSB overvoltage control ------ Normal (may need to increase if high FSB, usually if bus speed more than 450mhz)
(G)MCH overvoltage control - Normal (may need to increase if high FSB, usually if bus speed more than 450mhz)
CPU voltage control (very important) - let's mildly increase the vcore (+0.05v should be enough for now)
-E6750 - 1.400v
-Q6600 - 1.350v
-E2160 - 1.350v-1.400v (depending on your actual vcore)
-E8400 - 1.30v (depending on your actual vcore)
Normal CPU Vcore : (This is your stock vcore value, it will not change with OC)

Note : Make sure you double check your vcore is correctly set. You don't have to increase the vcore if you don't want too, but your OC will be lower

That's it! Save your settings. Reboot your computer. With the guide above, your computer SHOULD boot into windows without any problems.

At this stage, you have successfully OC your CPU:
E6750 - from 2.66Ghz to 3.04Ghz
Q6600 - from 2.4Ghz to 2.88Ghz
E2160 - from 1.8Ghz to 2.52Ghz
E8400 - from 3.0Ghz to 3.6Ghz

However, you need to test for stability in windows......

If your rig can't boot or hanged during windows
Probably too high overclock or too low vcore
Don't increase your vcore yet
Lower your bus speed instead, then try to reboot



-------- Part 2 : Assessing Stability of your first OC ----------

1) Start all the necessary programs:
- CPUz
- Core Temp
- Prime95

>> You can see your OC results in CPUz. It should show:
E6750
--- Core speed : 3040mhz
--- Multiplier ---: 8x
--- Bus speed -: 380mhz

Q6600
--- Core speed : 2880mhz
--- Multiplier --: 9x
--- Bus speed -: 320mhz

E2160
--- Core speed : 2520mhz
--- Multiplier ---: 9x
--- Bus speed -: 280mhz

E8400
--- Core speed : 3600mhz
--- Multiplier ---: 9x
--- Bus speed -: 400mhz

>>Common problem : Wrong core speed in CPUz. Multiplier of 6x!
--- This means the power saving mode is still enabled
--- Make sure you disable EIST and C1E in BIOS
--- Set windows power scheme to "Always on"
--- However, if it still doesn't work, it doesn't really matter, as once you stress your CPU, the multiplier/core speed will go back to normal.....

>> Look at core temp, you can see the temperature for all your cores at idle
--- Important : You need to observe the core temperature when you're stressing your CPU using prime95
--- Max core temperature : Preferably not to exceed 60-65'c

>> Look at CPUz's processor voltage - this will tell you your Vcore at idle and later at load
--- Note : It is not that accurate but looks like most people is using this as a rough vcore reading....

2) Stress your CPU to make sure it is stable at this OC
--- Run prime95 using the "Small FFTs" option (and not the blend test or the In-place Large FFTs)
--- note that all cores are tested
--- Run the test for 15 minutes
--- if your OC is stable, there should not be any errors in any of the cores
--- note your load core temperature

That's it. If no errors, you can start to OC higher!!!


------------- Part 3 : Higher OC ---------------------------

Now you can OC higher by using Easytune5 or any other software that comes with your mobo.

Don't stop prime95. Let it continue to stress your CPU...

Look at Easytune5 : Overclocking button : Advance tab
- Look at FSB (that's your bus speed)
----- at 380mhz (E6750)
----- at 320mhz (Q6600)
----- at 280mhz (E2160)
----- at 400mhz (E8400)
- This is where you OC your CPU further
- Increase the FSB by 5 mhz (your core speed will increased by +40mhz)
- DON'T FORGET to press the "GO" button to set the new setting
- Let prime95 run for 5 minutes
- if no errors, increase another 5 mhz....
- Do this until you get errors in Prime95
- Once you get errors, reduce the fsb by 5 mhz (This is your OC limit for the vcore that you set)

Once you get errors, you have 2 options:
1) You are happy with your OC and don't want to OC higher than that
--- In that case, just run prime95 to stress the CPU to check for stability
2) You want to go higher
--- In that case, go back to BIOS, and set a higher vcore e.g. for the E6750, increase from 1.400v to 1.425v
--- Boot into windows and check for stability

Note : ALWAYS watch your core temperature....


------------- Part 4 : Checking for stability of your OC --------------

Duration to check for stability : 6-12 hours (preferably)
Program to use : Prime95
- You can use other programs like OCCT, everest, etc
- There shouldn't be any errors in any of the 4 cores
- If errors, you need to reduce your FSB by 2-3mhz and re-run the stress program


--------------- Part 5 : What is safe vcore & core temperature? -------------------------

Safe max vcore?
When you overvolt your CPU, there is no safe vcore. The higher you go, the higher the risk of damage.
General recommendation : 5-10% of your stock vcore (Not overvolting more than that)
-- e.g. stock vcore 1.35v - preferably not more than 1.412v (5% overvolt) - 1.485v (10% overvolt)
This applies to air-cooling HSF only

Safe max core temperature?
Again, no max safe temperature. The higher you go, the more risky it is
General recommendation : 60-65'c (not exceeding, preferably)

Note : Having said all this, there are sources that say it is difficult to kill a CPU unless you intend to do it. Stay within the recommended values and you are quite safe....

----------------- Part 6 : Should I reduce my CPU multiplier? -----------------------

The answer would be a definite "yes" IF your mobo, northbridge and RAMs can keep up.
--- Mobo has to run at higher FSB
--- Northbridge has to run with divider (have to check on this, my sisoft sandra app not working properly) - thx to bryaneo87
--- RAMs may have to run at higher speed even though at lowest multiplier

Why? With a lower multiplier, the bus speed is higher. So, for the same speed, your rig is communicating faster with each other, which results in a slightly faster system....

Lets take an example, you have the following components:
1) E6750 (8 x 333 = 2.66Ghz) - able to OC stable at 8 x 425 = 3.4 Ghz
2) RAMs - running at 2.0 x 425 = 850mhz 5-5-5-15 (able to run stable at 880mhz 5-5-5-15)

If you reduce the multiplier to 7x, you need to increase the bus speed to 485mhz = 7 x 485 = 3.4 Ghz

So, if you mobo can run at a bus speed of 485mhz, then it should be ok

However, the rams won't be able to run at 2.0 x 485= 970mhz!!! (As the lowest multiplier is 2.0x)


------------- Part 7 : RAM settings after OC ---------------------------------------------

This is the tricky part
I'm describing how to set your rams to as near to you original RAM settings as possible
If you want to OC your rams, you need to look at other guides

Let's say you have these RAMS:
DDR2-800 @ 4-4-4-8 @ 1.8v (prior to overclocking)

As your E6750 was running at 2.66Ghz (8x333mhz), your original bus speed was 333mhz
So, your rams running at 800mhz would be using a 2.4x multiplier = 2.4 x 333 = 800mhz

Understand so far?

Now, when you started your overclocking, you set the ram multiplier to 2.0x (Downclocking the rams)
That means, your ram was running at 333mhz x 2.0 = 666mhz
Get it?

The reason you downclock your rams is so that when you OC, the errors that you get in stressing your computer is not due to the rams.

Let's presumed you have OC your E6750 to 3.2Ghz (8 x 400mhz) from 2.66Ghz (8 x 333mhz)
So, instead of running 666mhz (2x333mhz), your rams are running 800mhz (2.0 x 400mhz)

End result of the above example:
- E6750 OC to 3.2Ghz (8x400mhz)
- RAMs running at 2.0x multiplier @ 800mhz @ 4-4-4-8 @ 1.8v (which is perfect, as that's the original setting for the rams anyway)

>> In this case, you don't have to change the ram multiplier anymore as your rams are running at the same speed before the OC.

If you did not change the multiplier, your rams would be running at 2.4 x 400mhz = 960mhz
If your rams can do 960mhz at 4-4-4-8 @ 1.8v, then you would not have much problems
However, not many rams can do such timings

Understand?

Let me give you some more simple examples......

Example 1
E6750 OC to 3.4Ghz (8x 425mhz)
RAMs can run stable at 1050mhz at 5-5-5-10 @ 2.2v
For gigabyte mobos, the ram multipliers that are available are 2.0, 2.4, 2.5, 3.0, 3.5, etc

So, in this case, you have a few options for the multiplier:
2.0x = 2.0 x 425mhz = 850mhz (Much much lower than ram limit)
2.4x = 2.4 x 425mhz = 1020mhz (Below ram limit)
2.5x = 2.5 x 425mhz = 1062mhz (Over your ram limit)
3.0x = 3.0 x 425mhz = 1275mhz (Over your ram limit)

In this case, the best multiplier to choose would be the 2.4x, making your rams run at 1020mhz (as close to 1050mhz as possible)

Example 2
Q6600 OC to 2.7Ghz (9 x 300mhz)
RAMs can run stable at 920mhz @ 4-4-4-8 @ 2.1v

So, the options are:
2.0x = 2.0 x 300mhz = 600mhz (Too low dude )
2.4x = 2.4 x 300mhz = 720mhz (Nope )
2.5x = (Lazy to calculate )
3.0x = 3.0 x 300mhz = 900mhz (Just below your ram limit )
3.5x = 3.5 x 300mhz = 1050mhz (over limit )

So, the best setting for your rams would be with a multiplier of 3.0x = 900mhz
So your rams would run at 900mhz @ 4-4-4-8 @ 2.1v (which is just 20mhz below your max ram speed)

----------------- Part 8 : What is vdroop/vdrop? ------------------------

Important :
Software readings of vcore/voltages are not that accurate
The best is to use a digital multimeter (DMM) to measure the voltages
(Explanation as I understand it, pls pm me if some facts are wrong)

Easy explanation:
BIOS set vcore : 1.400v
CPUz vcore at idle : 1.380v (This is vdrop = 1.400-1.380v = 0.020v)
CPUz vcore at load : 1.350v (This is vdroop = 1.380-1.350v = 0.030v)

Vdrop - difference between bios set vcore and idle real vcore ("idle" means your computer is not doing anything)
Vdroop - difference between idle real vcore and load real vcore ("load" means your computer is running at 100%)

Facts on vdroop (@ load line droop):
1) It is not a flawed design
2) It is part of a power delivery design, to help reduce output-voltage spikes (e.g. like lightning strikes that can cause a sudden spike in the power lines and damage your electrical stuff...... yeah I know, poor example, but you get what I mean )
- power to the CPU is through the Voltage Regulator Module (VRM) circuit (consist of many parts like MOSFET, chokes & capacitors)
3) Without vdroop - any huge voltage spikes can go over a specification limit (thus increasing risk of damage)
- most critical when your CPU goes from load to idle
- overcharged MOSFET will lead to a spike in the CPU voltage
- results in repetitive spikes of higher voltage to the CPU, increasing the risk of damage to the CPU/Mosfet overtime
4) Vdroop can be reduced if a mobo has:
- A well-designed power delivery system/VRM
- A VRM with supposedly more phases e.g. 8-phase or virtual 12-phase (controversial)
- modding the mobo (for extreme overclockers!!!
- enable "Loadline calibration" in BIOS (see below)

Note : I'm have NO knowledge whatsoever in power circuits.... just trying to explain as simple as I can from what I read....

Importance of vdroop:
You want your rig to have as little vdroop as possible
With less vdroop, the actual vcore at load would drop less, enabling you to OC your CPU better

Example (assuming there is a vdrop of 0.02v):
- An E6750 can OC to 3.5Ghz @ 1.37v actual vcore
- Your mobo has a vdroop of 0.03v
- So, in order to get the E6750 stable at 3.5Ghz, you have to set your BIOS vcore to 1.42v

This is what happens:
- Bios Vcore : 1.42v
- Windows CPUz at idle : 1.40v (due to vdrop)
- Windows CPUz at load : 1.37v (due to vdroop) - YEAH! Enough vcore to run at 3.5Ghz stable!!!!

Understand aaa?

Technical explanation of vdroop : http://www.thetechrepository.com/showthread.php?t=126
Easier to understand explanation : http://www.anandtech.com/cpuchipsets/intel...aspx?i=3184&p=5

Loadline calibration
Unfortunately, the P35-DS3 doesn't have this setting in bios
For some higher-end mobos, you have this option in BIOS
If you "Enable" loadline calibration in BIOS, it actually reduces the amount of vdroop at load !!!

Note : May not be a good idea for 45nm CPUs. You have to try it out to confirm whether it is true or not. See here : Issue of loadline calibration with 45nm CPUs

----------- Part 9 : What is FSB wall? --------------------

Without going into too much details on what determines the FSB wall, I will make it as simple as I can (just for your info, the FSB wall can be influenced by factors such as your other PC components, FSB-strap, PLL/GTL Ref Voltages and ?vMCH/vFSB)

The "wall" just means that it is the limit/maximum OC that you can go.
For FSB wall, it means that you have increased your FSB speed to a certain point that it becomes unstable/unbootable no matter what you do.

E.g. You are stable at a bus speed of 450mhz (FSB of 450 x 4 = 1800mhz)..... if you increase bus speed to 451mhz, your system becomes unstable no matter what you do. So, 451mhz is your FSB wall.....

Again, without going into much details, the FSB wall can be due to either your CPU, motherboard or RAMs

Important : For the GA-P35-DS3, you usually need to increase you vMCH and vFSB by +0.1-0.2v if the FSB is high, usually above 450mhz..... try it at see if you hit a FSB wall....

----------- Part 10 : What is FSB strap? --------------------

I can't get much information on FSB strap for newer chipsets.

Apparently, this issue has been resolved and is not a major problem in overclocking for newer chipsets such as the P35/X38/X48. As such, I will not be going into details of the FSB strap.

It was a problem for the older P965 chipset.

Here are some references you can read about regarding the FSB strap
http://www.thetechrepository.com/showthread.php?t=30
http://www.xtremesystems.org/forums/showthread.php?t=128913

References
Another excellent and very detailed overclocking guide by graysky: http://www.tomshardware.com/forum/240001-2...ads-duals-guide

This post has been edited by kmarc: Sep 8 2008, 08:06 PM