i7 overclocking guide
alright, this is my first guide so dont judge me on anything.
alrite, so when intel released the core i7 they got rid of the FSB (front side bus) and added a few things (base clock, turbo mode, uncore, QPI (quick path interconnect)) i'm going to go over each.
So instead of the front side, something called base clock has been added, pretty much what it is is the main reference clock for the cpu, RAM, and uncore, meaning that if you raise it, you're also raising the frequency of the RAM, and the uncore (L3 cache, memory controller, and quick path interconnect, more on this later). On most of the i7 procs the base clock is 133 MHz. Most overclocking methods will require you to raise it past that (excluding the extreme edition i7 as it has an unlocked multiplier).
Some BIOS refer the Base clock as the bclock, host clock, or reference clock.
One of the things that hasnt changed is the multiplier, the core i7 920 has a multiplier of 20 and is locked so it can only be moved downward, the extreme edition has an unlocked multiplier of 24 so you can move it up or down. As with the past intel cpu's the total clock speed of the proc is derived by multiplying the base clock by the cpu multiplier. for the extreme edition 965 take 24 and multiply it by 133 to get 3200 MHz or 3.2 GHz. for the 920, 20x133 gives you 2667 MHz or 2.6 GHz.
One of the new additions is turbo mode. When activated (in the BIOS) it automatically overclocks a single core of the cpu when you're using single thread apps. if you've overclocked a core i7 920 to 3.66 GHz and turn turbo mode on, in single thread apps it will run att 4.03 GHz. In dual thread apps its possible to get a 1x multiplier boost. the only chip where you can set your turbo mode settings is the extreme edition i7.
UNCORE and RAM overclocking
the core i7 has two main areas, the uncore and the core. in the chip the execution cores that do the heavy lifting are the core, while the other parts (memory controller, L3 chache, and the quick path interconnect) are called the uncore. The only cpu that lets you play with the uncore multipliers is the extreme edition. so if you have a budget i7, the only way to raise this is to bump up the base clock.
One thing to remember when you're overclocking is that the uncore has to be twice the speed of the systems RAM. The speed of the uncore is determined by multiplying the uncore multiplier by the base clock.
For example if the uncore multiplier is say 16, 16x133 gives you 2.1 GHz. to get the RAM speed all you have to do is take the RAM multiplier and multiply it by the base clock. With the i7 the default RAM multiplier is 8. so to determine the main memory speed multiply 8 by 133. which gives 1066 MHz, if you got ram that runs at higher than this you'll have to overclock it to give you the stock speed. The only way to overclock it by raising the multiplier is once again using the extreme edition. with all the other i7's you'll have to stick with raising the base clock. The thing to remember here is that the uncore has to be twice the speed of the RAM, so if youre running DDR3 1333 the uncore speed has to be 2.6 GHz. Most BIOS's correct the ratios for you.
Something else that's new with the i7 is the Quick Path interconnect, This connects the processor to the chipset. The extreme edition's QPI runs at 6.4 gigatransfers per second. while the i7 920 and 940 run at 4.8. The QPI is important because if you raise it to much it can kill your overclock. For example if you raise the baseclock on an 17 to 200MHz that means the QPI will run at 7.2 gigatransfers per second which is a lot more speed that the stock 4.8.
The QPI speed of the 920 and 940 is derived by multiplying the baseclock by 36. which is 4788 or 4.8 GT/s. The extreme edition uses a default multiplier of 48, but is unlocked so it can be raised up or down.
The default voltage of the i7 procs is 1.2 volts, a recommended maximum voltage is 1.375 (if you have good enough cooling) any higher than that will require water cooling or better. Another area that needs to be overvolted is the QPI. you'll likely have to increase it to atleast 1.2 (from the stock 1.1) but dont be afraid to go higher.
The last you'll have to overvolt is the RAM. The highest voltage recommended by intel is 1.65 volts, but it can go a little higher.
The highest recommeded temps of all i7's is 67.9 degrees celsius. If all cores are running at 82 you'll be fine in the short term (probably enough to finish your crysis gaming session) but dont expect it to last 5 years. A safe temp is probably 70 C or lower.
Pretty much, if you just got a brand new 920 i7, good quality psu, and good coolinh and you want to overclock it, the best thing to do is set the base clock higher, say from 133 to 160. now run some stress test (prime 95 is good) or multithread apps to but some load on the cpu. If it runs for half an hour (or more, depending on how paranoid you are) then you can raise the base clock another 5-10 MHz. Keep doing this until the CPU fails. When it does, add some more voltage. a good starting point is 3.4-3.75 on the cpu. Also you might want to raise the QPI voltage while you're at it (say 1.1 to 1.2-1.3). Also add voltage to the RAM to get it to the voltage the maker recommends (you can find it in the specifications). Now reboot and run the stress tests again. keep repeating these steps until you can't go any farther.
In conclusion, don't blame me if you kill your cpu. Overclocking is a risky process so do it at your own risk. If, for whatever reason you can't boot, look in your motherboard manual for how to reset the bios, (usually a jumper or something like that) and do it, which will put everything back at stock speeds. Feel free to correct me or add anything you like. This is my first guide though, so try not to be to mean.
intel core-i7 920 4+ GHz with the thermaltech 120 extreme with adition 120mm fan lapped. mobo: asus p6t deluxe gpu: Sapphire 5870 OCED. PSU: power pc and cooling 910 watt RAM: Corsair 6GB ddr3 1600 HDD: two 640 Gb WB Caviar in RAID 0: coolermaster haf 932 with all red fans
monitor: samsung ToC T260 roseblack 25.5" 5ms 1920x1200