Intel Core i7-975 XE Review - D0 Processor Stepping in Action

@ 2009/04/22
It is evident that it doesn’t make sense from the performance prospective to compare the CPUs with new and old processor stepping. Since Intel didn’t introduce any new technologies and didn’t make any architectural changes, CPUs with C0 and D0 processor steppings working at the same clock speeds will perform equally fast in regular benchmarks. That is why it is not very interesting to dwell on performance of the new Core i7-975 XE in our today’s article. However, the heat dissipation and power consumption measurements are, on the contrary, extremely interesting to perform. This is what we are going to do next.


Comment from Kougar @ 2009/04/24
Quote:
Originally Posted by geoffrey View Post
In that case, where is the technological progress?
Higher overclocks at lower voltages with more consistency. Sounds like technological progress to me?

XS is full of reports of people OCing D0 steppings on air as far as their C0s on water, some report their D0 overclocks on water better than their own C0 chips did on DICE(!). It makes the B3 -> G0 Q6600 stepping change look like nothing.

Anandtech's first and (previously) only retail D0 Core i7 920 overclocked as good as their best C0 965 & 920 chips and did so using lower voltages on everything. To quote them:

Quote:
Originally Posted by Anandtech
We enabled Turbo mode on all four cores for a final 21x CPU multiplier, set Bclk to 205, memory ratio to 2:10, Core VID at 1.345V, VTT to 1.37V, IOH to 1.19V, and VDimm at 1.69V. This resulted in a final CPU speed of 4.309 GHz, memory speed at 2052 with 7-8-7-20 1T timings, and it is 24/7 stable.

First off, none of the C0 steppings we have would operate at these particular voltage settings, in fact two of them failed to POST. Our best C0 sample is requiring 1.425V on Core Vid, 1.250V IOH, 1.475V VTT, and 1.71V VDimm to just make it into Vista Ultimate 64 and we still have not dialed in application stability yet.
Some on XS are running benches with their 920 D0's between 4.5 and 4.7GHz on air using <1.5v. Core i7 920 D0 looks to be a better overclocker than the Core i7 965 was in many cases. Key phrase seems to be retail kits, Xbit used an ES sample here and stayed below 1.40v.
Comment from jmke @ 2009/04/22
is that reply aimed at me?
Comment from geoffrey @ 2009/04/22
In that case, where is the technological progress?
Comment from jmke @ 2009/04/22
but stepping could include lower VID to reach same speed!
Comment from Rutar @ 2009/04/22
Couldn't the VID be the influencing factor in this comparison and not the stepping?