i7 overclocking for beginners

[NicoOCZ]

In this thread I'd like to introduce you to overclocking your i7 system. It's much easier than you might think and a proper amusement for a dark and cold winter evening ;)

Please note: We're just making suggestions and try to guide you. I can't stress enough that if you try our hints, you do so at your own risk! OCZ will not be responsible for any damage caused by following this guide.

Here's the system I'm going to use:


Intel Core i7-965 EE
ASUS Rampage II Extreme (BIOS 1802)
6GB DDR3-1333 (OCZ3P1333LV6GK)
ATI Radeon 4890
2x OCZ Vertex 60GB RAID0 on ICH10R
OCZ Z850
CPU watercooled by OCZ Hydroflow
Windows 7 x64


Tools we need:


LinX (http://www.xtremesystems.org/forums/showthread.php?t=201670) (stability testing)
CPU-Z (http://www.cpuid.com/cpuz.php) (system information)
ASUS PC Probe II (http://www.asus.com/product.aspx?P_ID=W7i5W4Pw4fH22Mih&content=download) (voltages and temperatures)


Things you need to know when overclocking an i7 system:


Do not exceed safe voltages. I suggest not to exceed 1.35V CPU VCore, 1.90V CPU PLL, 1.35V QPI and 1.65V RAM
UCLK must be at least DRAM Frequency x2 (Example: DDR3-1600 -> at least UCLK Frequency 3200MHz)
Always keep an eye on temperatures. CPU temperature should not exceed 70°C




1.) Getting started

First of all, make sure you have the latest BIOS version installed. Newer versions always come with bugfixes, enhanced memory compatibility, new CPU support, etc. Once your system is up and running, head to the BIOS. It's always a good idea to disable all onboard features you don't need, in my case that is onboard sound, Firewire and the secondary SATA controller. For best overclocking results you also want to disable all CPU features related to power saving like EIST and Speedstep. With a Low Voltage memory kit you will have to set your memory voltage to 1.65V. I suggest a quick run of LinX with these default settings to make sure your system is perfectly stable. There's no point in overclocking an unstable system, right?



2.) Mild overclocking

My CPU runs at 3200MHz by default, 24x133. In this guide I want to show how to overclock your system by increasing the so-called base clock (BCLK). First try is to increase BCLK to 166 and lower the multiplier to 22x, which would result in 22x166 = 3660MHz. That is a rather mild overclock that any i7 should be able to handle. I had to bump the CPU voltage (VCore) to 1.275V, CPU PLL to 1.89V and QPI/DRAM to 1.32V to stabilize my system. I also set Uncore (UCLK) to 3327MHz. Please note that Uncore must be at least DRAM frequency x2. Talking about DRAM frequency - I lowered the memory multiplier to make the memory run at 1664MHz with BCLK 166. My CPU is from an early batch and not a big fan of overclocking. Newer batches might do way better here. I fired up LinX, configured it to use all available memory for the test and have it run for 60 minutes.


http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=13923&d=1266591685 http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=13922&d=1266591683 http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=13925&d=1266591693

http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=13924&d=1266591691

[NicoOCZ]

Now if you're willing to get an even better result, we need find a) the maximum BCLK, b) the maximum CPU clock and c) the maximum memory clock. We need to determine each value on it's own first to find the best match of the results we get.



1.) Maximum BCLK

To determine your systems maximum BCLK, lower the CPU multiplier to 12x and also decrease the memory multiplier to the lowest value. We need to rule out all other components as limiting factors. I decreased the CPU multi to 12x, increased CPU PLL to 1.89V, QPI to 1.32V and ended up with a maximum BCLK of 213MHz. Not that good, not that bad, just about average.

http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=14125&d=1267710708


2.) Maximum CPU clock

Again we need to make sure no other component is limiting our tests here. So we decrease the memory multiplier to the lowest value, BCLK to 200MHz and raise the CPU multiplier to 20x. Along with 1.35V and QPI 1.34V I was able to achieve a solid 4GHz. This was the maximum I was able to achieve within reasonable voltages.

http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=14141&d=1267807446


3.) Maximum RAM clock

You might have guessed it - once again we need to make sure no other component is limiting our test, hence we decrease the CPU multiplier once again. My OCZ3P1333LVA6GK is specified for 1333MHz at 7-7-7 with 1.65V. I was able to overclock this kit to 1724MHz at 8-8-8 with 1.65V. I had to increase QPI to 1.35V to stabilize the system.

http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=14156&d=1267885755



4.) The sum of our achievements
Alright, now we know the limits of our components. We need to find the best mix of settings to optimize this system. I choose the following:


CPU clock = 3956MHz
DRAM clock = 1724MHz

CPU ratio: 23X
BCLK: 172MHz
UCLK: 3448MHz
QPI Link: 6208MT/s
Timings: 8-8-8-24 2T
CPU VCore: 1.35V
QPI: 1.35V
CPU PLL: 1.89V
DRAM: 1.65V


Why did I choose these settings? Here's why. One alternative would have been running the CPU at 20x200, which would allow 4000MHz. With the RAM multipliers on this board I'd have to choose between DDR3-1600 and DDR3-2000. 2000 is way too much for my RAM and 1600 is below it's limit. So I ended up sacrificing 50MHz of my CPU frequency to gain 124MHz RAM frequency.

http://www.ocztechnologyforum.com/forum/attachment.php?attachmentid=14157&d=1267885760