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Old July 17, 2009, 09:25 PM
keto keto is offline
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Join Date: Jul 2009
Location: Edmonton
Posts: 265
Default My i7 Overclocking Experience - Air Cooled

If there's interest, I'll continue detailing my ongoing overclocking trials.

-i7 920 C0 (HS NOT lapped)
-True 120 Black (NOT lapped) c/w 2@1600 cfm in push pull, open case, no other case fans, ambient typically 23C in air conditioned house.
-Gigabyte EX58-UD5
-6GB OCZ DDR3 14400 PC1800, triple channel configuration
-Sapphire 4890 1GB OC Edition
-Seagate 500GB HD
-PCP&C 750 Crossfire PSU

As I sit here, I am at 19x200 = 3.8, vcore 1.3650, CPU PLL 1.880
-Load Line disabled
-HT OFF
-Turbo OFF
-power saving features OFF.
-RealTemp3.0 says I'm idling at 45/42/43/44.
-Full load temps with 4 (Not 8, HT is off remember) iterations blend P95 maxed @ 69/68/65/65
-RAM is 8x200 = 1600, vdimm 1.660 (no bios adjustment for spec 1.650), VTT 1.520
-Uncore 17 (RAM MULTI X2 +1) (8*2+1)
-QPI x36 (lowest in bios)

I'm not gonna flood my posts with screenies. You will find my numbers are not going to blow anyone away, so I feel no need to do the extra work to validate. If you have any questions, I will do my best to answer them.

This is stable, based on blend P95. 3DM06 = 19072, SuperPi 1M 10.892s. I haven't loaded up any other benchmarks yet, though I will be shortly.

My only ongoing concern is VTT....but the Gigabyte article on overclocking the EX58 series references 1.515 being used, I don't get that option but .020 increments. 1.500 proved unstable in some earlier testing, so I've just left it at 1.520 for now. Most user experiences I have read show much lower VTT voltages stable at high overclocks. Unless I misunderstand something, Intel's max spec is 1.350. This particular setting does not seem to impact core temps.

Previously, I was stable at 21x172 = 3.612, vcore 1.350, WITH HT WITH powersaving WITH Turbo, mem @ 10 (so 1720) and Uncore at 21. 3DM06 was 18987, SuperPi 1M 11.482s. Idle temps were 41-42, load temps (8 iterations of P95 blend) 76 max. I have had great difficulty going up from this with all features enabled. That said, I have not bumped voltage up to my (floating in my head still, not carved in stone yet) ceiling of 1.450v.

For now, just for the helluvit, I'm going to keep the HT/Turbo/power saving off and see how high I can take this chip. My expectation is that, in this bare bones/reduced features configuration, I will probably see 4.0 and maybe a touch over, at reasonable temps and voltages. Load temp of 69 at current configuration is relatively low, many users who use air cooling report peak temps in the mid 80's as being 24/7 stable - that is, not mid 80's all the time, but an overclock that itself has occasional peak temps there. Most others are in the mid to high 70's peak on air. Built in chip throttling doesn't seem to kick in until well into the 90s.

I've done many hundreds of pages of reading of posts from various forums, reviews, tech articles, etc. in the past week. Still have a couple of minor concepts and wording differences among manufacturers to solidify in my mind, but I think I have a handle on this.

For anyone wondering about D0 stepping vs C0 stepping, the headroom seems to be not with the air cooled guys (n gals) or even the water setups, but more headroom with phase change systems definitely. D0's can run on lower voltage - what I am seeing is D0's @ 4.0 around 1.20-1.25vcore, wheras the C0's need in the 1.3's and up - but the D0's seem to natively generate much more heat, and temps are generally higher at head to head clock speed vs a C0. Beyond that, there are more desireable batches of both C0's and D0's, and lesser chips of both also. But the big numbers you will see from the phase change guys are almost universally D0's.

At least that's my unscientific observation.

Off to try 20X200 or 19X210 or something, see if I can crack 4.0. Even where I'm at 3.8, I haven't owned a chip with this much headroom over stock speed (43% so far!) in many many years if ever.....I'll think about that one some more and try to remember. I missed out on the great Celerons (366? I forget) that would almost double speed back in the day.

Yes, when I get started I am absolutely capable of producing a wall of text
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