Intel’s Core i5-655K & Core i7-875K: Overclocked and Analyzed
by Rajinder Gill on May 28, 2010 5:00 AM ESTFinal Words: Not for Enthusiasts
This is another of those situations where we’ve had to make an eleventh-hour conference call with Intel to work out what and who these processors are aimed at. Our initial perception of this launch turned out to be wrong - because we thought we'd see some kind of additional overclocking overhead from the K-series SKUs that would make them stand out from the crowd.
Our perceptions changed when Intel told us that they will not be binning these processors in a special way or marketing them at die-hard overclockers, but instead at system builders who can utilize the unlocked core features to provide cheap pre-overclocked systems with minimal fuss. In the same vein, the K-series will allow users to purchase cheap motherboards that don’t need overly complex BIOS options as we only need control of core multiplier ratios and VCore to get a quick and easy overclock. Bearing these aspects in mind, it’s hard for us to be negative about this launch; however, we’d like to see Intel unlock more processors in the future.
Out of the two processors Intel have launched today, it's the i7-875K that hits the mark on price. Sure, it's not going to set the world on fire with overclocking records but it does present users who are in the market for an all-round cruncher with a viable alternative to the AMD 1090T and the Intel i7-860 without breaking the bank.
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Rajinder Gill - Saturday, May 29, 2010 - link
Hi,I ran out of time to test any further unfortunately. The emphasis was kept on air/water cooling because it's practical to run 24/7.
Regards
Raja
TheBLK - Saturday, May 29, 2010 - link
I'll ask again. Unless the screen shots are wrong you used BLK clock to over-clock rather than multiplier on the chip.Other reviews kept the BLK at the same value and just used the multiplier and seemed to get higher results.
Rajinder Gill - Saturday, May 29, 2010 - link
Yes I did on the 655-K stock VID (added 2 BCLK because the next multiplier up was too far (133 multiples in frequency is a large jump) :http://www.anandtech.com/show/3742/intels-core-i56...
Also describe why BCLK overclocking is not the way to go on the 655K for performance:
http://www.anandtech.com/show/3742/intels-core-i56...
Finally the 855K - this chip is limited to 4GHz even on water cooling. BCLK overclocking is not going to change that. 167 BCLK at DDR3 1670 is nowhere near stressful for the Lynnfield IMC. Multiplier overclocking is NOT going to make any difference to the clock speed limitation.
-Raja
Rajinder Gill - Saturday, May 29, 2010 - link
Just for you :)http://img7.imageshack.us/f/linpackfailj.jpg/
That is all the water loop can handle (the chip is drawing over 190W). I can drop the multiplier down to 30 (but then we are back to 4GHz).
Hope this helps!
Regards
Raja
DJMiggy - Thursday, June 3, 2010 - link
It seems like you guys used the wrong motherboard or got a dud i7. Other reviewers don't seem to be having as tough a time overclocking these higher.Rajinder Gill - Friday, June 4, 2010 - link
The motherboard is EVGA's E659 - works fine with my i7 870 ES taking it to 4.4GHz Linpack stable. It's the CPU that is the limiting factor here. Bear in mind that not all articles you've read will have stability checked stability with Linpack as well.Later
Raja
DJMiggy - Friday, June 4, 2010 - link
That makes sense. Cool thanks! I appreciate the explanation.ReaM - Saturday, June 5, 2010 - link
I must say, what a crappy K-series! I can bring every i7 860 up to 4ghz. I have tested many of them, so there is really no reason to put any hope into these Ks. Just buy a regular one.My personal sample of 860 runs @ 4200 with 1.29V on air Noctua U12 with low temps.
ReaM - Saturday, June 5, 2010 - link
Did you put Load Line Calibration into LVL2?I don't know what's that called on EVGA. Enhanced Power Slope. VDrop Adjustment. Lynnfield, unlike Bloomfield, likes their load line to be adjusted.
Rajinder Gill - Sunday, June 6, 2010 - link
Makes no difference to the stability of this chip.