Phenom II runs a lot cooler than Core i7

Silicon-on-Insulator(SOI) paying off for AMD.

Both the Core i7 and the Phenom II are built with a 45nm lithography process, the difference is that AMD uses SOI, introduced years ago, to further reduce current leakage that plagues current and past generations of processors. While Intel has also introduced metal gates in their 45nm process - with quite some success - current processors seem to be wasting a lot of power. Just take a look at these two charts:

Clocks and voltage:

• Intel Core i7 920 @ 3.97GHz, 1.3625v
• AMD Phenom II X4 940 @ 3.81GHz, 1.55v
  

Granted that the Phenom II X4 needs more volts to reach similar clocks - and performance is worse - the almost 0.2v of difference is astounding when seeing the temperature charts. With the same Zalman cooler, the i7 is 24ºC warmer. If you have been overclocking your PCs you probably know that 0.2v of difference should've yielded you around 24ºC more for the Phenom II, not the Core i7. Mind you, the transistor budget is even very similar: 758M for the Phenom II and 731M in the Core i7.

I had already noticed that my 90nm Athlon X2 was considerably cooler than the 65nm Core 2 Duo I once had and that the i7 that went by me did heat up a lot - 80ºC with the stock cooler - I just never had the change to do a direct comparison. Also, the same Core i7 920 I experimented with, reached 67ºC, at stock speed, with a Xigmatek S-1283 in full speed, the same as the Phenom II X4 heavily overclocked here.

If you're looking for the top performance, the Core i7 is the way to go right now; if otherwise a balanced machine which doesn't make much noise is what's on your mind, these new findings should help you make your mind - very good overclocks that don't require more expensive cooling for either the CPU or the rest of the components and that also fit in a smaller platform budget.

Zalman CNPS-10X review @ Xbitlabs