Ok, so we got a little carried away on the Clarkdale stuff. Time to give the i7-875K a look-see. After all, it’s probably the bigger story of the K-series release given it offers more overclocking features and a similar stock clock speed to the more expensive i7-870.

No beating around on this one, we started off with watercooling:

click to enlarge
 
Things are fine up to 3.7GHz, but any higher and things soon get out of hand. CPUs like these are fine if you need a stock runner, or are looking for a basic overclock, although this kind of performance is easily available from the cheaper i7-860.
 

Without water-cooling, there isn’t much headroom at all - at least not on this sample. Our i7-870 ES manages 4.4GHz, pulling 201 Watts during Linpack. The 875-K is already at 193 watts, and it has barely broken 4GHz.  Past 3.9GHz, we’re already looking at a 10W increase in power consumption for every 20 MHz rise in CPU frequency - let’s just say that this did not encourage us to push any further. Well, that’s not completely true because we did try it out under our cascades. Unfortunately, things are pretty bad in the sub-zero realms, too. The substrate can’t handle more than 1.35Vcore when cooled below -70 Celsius, making it a difficult chip to control and one that’s ultimately limited in headroom. The best we managed was a run of Vantage at 4.5GHz, which really isn’t worth bragging about.

i5-655K Meets a Cold Snap Final Words
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  • wavetrex - Friday, May 28, 2010 - link

    In the table it sais $284 for the 980X, that MUST be a mistake!
  • mianmian - Friday, May 28, 2010 - link

    In a previous Anandtech aritical, it was $999, maybe it is $824 now
  • Texpat - Friday, May 28, 2010 - link

    I think the price for the 980x might be wrong. $1,000 would be closer tot he truth.
  • ltcommanderdata - Friday, May 28, 2010 - link

    I'm really pleasantly surprised that the 2.93GHz Core i7 875K at $342 is cheaper yet has more features than the 2.93GHz Core i7 870 at $562. Although I'm guessing that's only temporary as the upcoming 3.06GHz Core i7 880 will probably take over the $562 price point, with the Core i7 870 dropping down to $284 and the Core i7 860 being phased out. There's also a Core i5 760 to replace the Core i5 750.
  • DrMrLordX - Friday, May 28, 2010 - link

    You guys really busted out the big guns with the dual-stage cascade! Please do this more often when overclocking. I would love to see a C3 Propus at -100C (or a Thuban).
  • jleach1 - Friday, May 28, 2010 - link

    On the second page, i believe in the 'test rig' table the proc is listed as a i5-870 instead of the i7-870
  • Rajinder Gill - Friday, May 28, 2010 - link

    Thanks - fixed!
  • GeorgeH - Friday, May 28, 2010 - link

    "it’s full of talk about voltages and harps on about overclocking"

    No need to be shy about that - Anandtech is bookmarked because of awesome articles and analyses like this one.
  • FlanK3r - Friday, May 28, 2010 - link

    not bad, my x6 1090T is full stable 4300MHz 2800MHz NB with aircooling ,-)...for games and benchmarks 4400-4450 MHz :)
  • AstroGuardian - Friday, May 28, 2010 - link

    Guys, i think you should not hurry to release articles instead of taking them slow and sure. Many typos especially in the graphs.

    i3-530 vs i5-540

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