OverclockingDid overclocking Change?
This is what all the enthusiasts have been waiting for, no? Early reports told us that the Core I7 would not be overclockable, later on the game we were told by various sources that overclocking would only be possible on the high-end products and thus highly expensive products. A massive amount of people responded, either confirming or invalidating these reports, really ... the overclocking part of this platform has been discussed a lot.
In the end, we can only look back and laugh, because overclocking mainly stayed the same: you can either increase the frequency by increasing BCLK, the base clock frequency, (~ FSB) or the multiplier (on unlocked processors). That's it! Of course, the limiting factors have been changed and the playing field has changed, but the most important part is completely the same, which is very good news for those who were afraid overclocking would never be the same.
Overclocking the BCLK isn't that difficult, but unlike the previous generation (well ... current generation) it's limited quite rapidly. No more 600MHz+, but fairly under the 200MHz barrier. In average that is, because we have seen people hit over 200MHz already, although that was on an Asus sample, not on the Intel Smackover we used for overclocking. This motherboard already went upto 195 MHz, achieved on the same Intel mainboard. ( link
). Unfortunately, I could only go up to 155 Fsb speed. But no worries, luckily we could also raise the multiplier as we had a Core i7 Extreme 965, which is unlocked, in our possession.Automatic overclock
As you could already see on the previous page, the Intel mainboard allows you to set various multiplier out of which the CPU can choose, depending on how hard it is used. So if you are using a lot of single core applications, the cpu will automatically scale up to perform better. Using multiple cores it still will be running overclock, but less high, to maintain stability.
And if something would fail cooling wise, the processor will first start to throttle (go to lower multiplier to consume less power) before it will turn itself eventually off complete to prevent damage.Results and some quickies ...
Because the Asus board had to be returned, the following overclocking results were done using the Intel mainboard. At first we were using the boxed cooler.
As already mentioned earlier, we could only achieve a 155 MHz base clock frequency, so we used the multiplier and BCLK combination to achieve the best results.
Using the boxed cooler:Default voltage (~1.15 Vcore): 26 x 144 MHz = 3780 MHz
Raised voltage to 1.3 Vcore: 29 x 140 MHz = 4060 MHz
Raised voltage to 1.4 Vcore: 30 x 140 MHz = 4200 MHz
We achieved a whopping 4200 MHz overclock, just using the boxed cooler. This was stable enough to run some benchmarks, but when we stressed al 4 cores (and using all 8 available threads), the cpu began throttling and became instable. So with a better air cooler, such as the Thermalright Ultra Extreme 1366 CPU Cooler, this frequency could be maintained stable.
But then I dug a bit around in my room, and found the Nventiv Mach 2 Phase Change cooling (What is phase change cooling ?). This unit has been refilled with R507 and modded by Jort for a better performance. So it should outperform a Mach 2 GT.
The setup ready to be fired up.
Home made mounting, made in just a few minutes.
Raised voltage to 1.55 Vcore: 32 x 140 MHz = 4480 MHz
This score was stable to run through a decent batch of benchmarks, but after a while it became instable. Because it was just after a while, we decided to push it a bit higher.
Raised voltage to 1.55 Vcore: 32 x 144 MHz = 4610 MHz
Hexus Pifast and Superpi 1M calculations at highest reached frequency.
So overall the overclocks were far from bad, but why didn't the system remain stable ? We tried to find this out on the next page.