Intel K Series Processors

Test Setup and Overclocking

Intel K Series  Processors

Test Setup and Overclocking

ASUS Maximus III Extreme P55
4GB Corsair Dominator (running at 10x)
ASUS HD5870
Corsair HX850
Noctua NH-D14 with MX3
Windows 7 Ultimate
Intel i7-870, Intel i7-875K, Intel i5-655K

We also tested a i7-930 for comparison, using the above but with 6GB of Corsair Dominator and a Rampage 3 Extreme. Although the i5-655K comes with an integrated graphics chip, for ease of comparison and because the chip hasn't changed since we last tested it, we'll be skipping that part of the testing.

Overclocking

Stand by and hold on tight. 8 CPU-z coming up, but thankfully the text is brief because the overclocking is easy.

i5-655K

Stock shot on the left. As is normal with overclocking, heat is the main issue. However with the 655 following the 650 in being a 32nm chip this shouldn't be an issue and sure enough it proved not to be so. A full Prime95 run with the chip at 4.45GHz doesn't even crack the 57°C mark. Now we have a serious air-cooler in play here, but even a standard 120 type will run this chip at 4 to 4.4GHz all day without a problem. So we've got quite a lot of overhead to push on with.

Intel K Series Processors      Intel K Series   Processors

Finding the highest stable speed we could run was simple as the even a complete neophyte to overclocking will be able to happily hit 4GHz thanks to the ease you can extract performance from this chip. With a rather hefty bit of voltage we managed to get 4.7GHz despite the extremely warm weather that England has experienced in the past week. Waiting until it got as cool as it's likely to we got just past 4.8GHz. A stunning overclock. We're convinced this chip can do 5GHz on air and would love to revisit this in the future.

As it is a 1.6GHz overclock which nobody could complain about. For our testing we're sticking with the 4.4GHz above to ensure stability.

Intel K Series  Processors     Intel K Series  Processors

i7-875K

Moving to the 875K, the results are somewhat less impressive. Although they would struggle to be as good as the 655K. Starting with the BCLK test we found 225MHz to be the limit, although the 1.36v needed to get to this small level is of some concern.

Intel K Series Processors     Intel K Series Processors  

The BCLK only going to 225 was a bit of a sign of things to come, as the main problem with the 875K is getting it stable at an kind of decent BCLK. Rather most of the overclocking has to be done using the multiplier.  Not being happy having to run over 1.4v as any kind of 24/7 overclock we knocked the multiplier down to 25 for a 4.28GHz overclock at 1.36v core.

Intel K Series Processors     Intel K Series Processors  

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Most Recent Comments

07-06-2010, 06:49:50

tinytomlogan
It's been a long while since we've seen an unlocked multiplier on a mainstream Intel. How do the K series fare?

Continue Reading

07-06-2010, 10:09:15

Steve-O-
When I finally upgrade I'll be looking for a quad-core since I do graphic work. Looks like the $930 is still the best deal. The 655 is pretty sweet though for a dual-core.

07-06-2010, 10:21:57

Diablo
Yeah, they seem expensive for what they deliver. If anyone was going to spend 300 on a CPU (or more), they would go for an X58, and clock the i7 930. The 1156 platform doesn't seem the logical place to stick these chips, although I suppose that intel don't want to put people off buying the extreme edition chips.

Good review, so good for OC3D, but weird price/platform of chips from intel.

07-06-2010, 11:05:37

AMDFTW
WOW thats extreme for aircooled over 5Ghz on water

07-06-2010, 11:06:40

tinytomlogan
the conclusion was difficult tbh as there were so many factors to consider. The 875 is cheaper than the 870 but doesnt seem as good. The 655 goes like stink but costs a good chunk more and seems expensive for a dual but it is 32nm.....

Its a tough one to call tbh.

07-06-2010, 15:09:20

Steve-O-
I hear ya Tom. Good review regardless. And I think fair scores for both.

07-06-2010, 15:16:49

FragTek
Looks good to me!!

07-06-2010, 16:19:17

Lallespasser
I think you've overlooked an important aspect. By overclocking only the multiplier, you are not forced to disable Turbo, enabling you to have an overclocked chip while still maintaining low idle power consumption. This would, at least for me, be an important factor when buying a CPU.

07-06-2010, 17:56:17

tinytomlogan
Quote:
Originally Posted by name='Lallespasser'
I think you've overlooked an important aspect. By overclocking only the multiplier, you are not forced to disable Turbo, enabling you to have an overclocked chip while still maintaining low idle power consumption. This would, at least for me, be an important factor when buying a CPU.
We overclocked the BCLK too fella as Bus speed is just as important for us, if for no other reason than to show what the cpu has to offer. 99% of overclockers are more interested in a high base clock more than a higher multiplier.

08-06-2010, 07:38:22

Rastalovich
Higher clock means faster for other componets too. An extreme cpu running at 6ghz with memory running in the 700s aint very clever.

I don't know about these offerings. The games seem to favor high(er) caches - which is weird.

31-08-2010, 05:33:10

Ari-M.
i got my 875k on the cheap....and must have scored a gem. the mem controller on my 875k is an absolute BEAST. my fill rates and latencies even surpass my x58 rig (by a staggering degree)

the 875k does fall pretty short on synthetic CPU benches....but I use it for audio production....in that environment (sample editing) memory speed trumps all....so the 875k does have an interesting little niche

it is well matched to the ASUS p7p55d
Reply
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