**Official** Core i7 860/870 overclocking thread

[ziggo0]

My first i7, got it up and running last night. EVGA P55 FTW, G.Skill Ripjaws, i7 870, it shoots up to around 1.3vcore - it's kinda hot but the rig is dead quiet, room is nice and warm. Apogee GTZ water block on it too.

[HadesHwMania]

Which Ripjaws are those? Can you show what's the limit in OC for that memories?

[ziggo0]

They are g.skill ddr3 1600, 7.8.7.24 1.65v, xmp reports its only 1.6v, i'll get more onto that soon. I had a buddy get the same set, i'll be heading down to his place for a oc lan LOL

[Kain665]

Very nice, what batch?

[Oztopher]

I was trying to get 3.8 with HT stable last night. First i tried 200x19, with a vcore and vtt which i was sure would be stable, it failed on the 2nd-3rd test of linpack. Playing with vtt did nothing. I then tried 190x20, same thing, failed on 2nd/3rd test. I then tried good old 181x21, and then it goes on to pass 21 tests... Vcore was the same, vtt was 1.19 which i remember ~180 bclk needing... now i see why people talk about the 21x multi.

But it's strange, because when going for 4ghz, i clearly remember 200x20 needing less vcore than 21x191? I tested this with HT on and off. Weird...

edit: and before anyone says it, it wasn't the RAM

[Kain665]

Test it longer. Chances are it was going to crash at 181x21, but it hadn't happened yet. I personally haven't seen any solid stability increases with odd multis, just being able to boot at higher frequencies.

[Oztopher]

It definitely does make a difference though, i tested a couple of times at 190x20 (1.25vtt) and 19x200(1.31vtt), (also testing variations of VTT) both failed within 3 tests of linpack (using 3gb). As soon as i tried 181x21 (1.17vtt), it goes on to pass 18 tests before i stopped it. Quite a difference there and it wasn't just a fluke.

But the thing was, at 191x21 (4ghz), it needs a solid 1.376v to at least run several tests of linpack, maybe even 1.392v to be stable. But at 200x20, i can run the tests with 1.36v and needing 1.376v to be pretty damn stable. Leading me to believe the higher bclk along with higher VTT allowed a lower vcore. But this wasn't the case when going for 3.8. This wasn't just once that i tested it either. I also tested it without HT (at both 3.8 and 4.0) and same thing. Just strange.
__

Right, got 3.8 stable. As this morning after leaving WCG running last night, i awoke to a 'uncorrectable hardware error' blue screen. In most cases for me this has been a lack of VTT (which was at 1.17). So i made sure to get it stable before my next crunching session. For some reason the gflops slowly went down after the ~20th test, it was averaging about 49.2 before that.




Vcore under was load was 1.280v/1.296v. Going to see what i can do at 200x19 just for 'scientific' purposes

__

Well, got it stable but it required a touch more on vcore bringing the loaded voltage up to 1.296v. I might try bring vtt down if i can. 200x20 with HT needed 1.33vtt, but due to the lower CPU clock it might need a notch less.

[Kain665]

If you only need 1.71v VTT for 181 Bclk, why do you need 1.25v for 190? Try 1.2 or 1.225v. Too much VTT can cause instability.

Also, I have found that Vcore is responsible for 124s as well as VTT.

[KURTZ]

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4000mhz ...

[Kain665]

Very nice, what batch?

[Oztopher]

If you only need 1.17v VTT for 181 Bclk, why do you need 1.25v for 190? Try 1.2 or 1.225v. Too much VTT can cause instability.

Also, I have found that Vcore is responsible for 124s as well as VTT.

Yeah my VTT scales badly, for 180->190->200bclk it goes 1.19->1.25->1.31vtt respectively.

Pretty sure 1.25vtt is the sweetspot for 190bclk. 1.21vtt blue screened after about 7 tests, 1.23vtt i'm guessing would be mostly stable but, 1.25vtt is rock solid.

image

4000mhz ...

That's pretty nice, low temps as well. Although, i only see ~44gflops there, you might want to re run and optimise that to make sure it's stressing thoroughly. You should be getting above 50 gflops for that clock.

[KURTZ]

Very nice, what batch?

L014B185

That's pretty nice, low temps as well. Although, i only see ~44gflops there, you might want to re run and optimise that to make sure it's stressing thoroughly. You should be getting above 50 gflops for that clock.

yes, i'm in trouble with the GFlops, i dunno why i get these flops ... i tried many different settings but i never get over 50gflops ... any tips?

[KURTZ]

just a quick test to see the gflops w/1.35 vCC & 1.35 vIMC ... (RAM ocd @ 2000 CL.9 w/1.65vDIMM)



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[Oztopher]

Well i was going to say it might be because of the low bclk/uncore etc. But your last post ruled that out

Try only using 3072mb in linx, and before u start it, run a quick custom prime95 blend test using 3400mb of memory, just to clear out any cached files etc. Run blend for a couple of minutes until the amount of available and cached memory in task manager drops to ~200-300mb.

Give it a try, i always do that before every linpack run and i get consistent amount of gflops everytime.

[Kain665]

Gflops are mainly dependant on two things, bar frequency - OS load, and memory throughput. Make sure all programs are closed and nothing unnecessary is running, and then run LinX. If it's still < 49+, then it's just your RAM.

Also, 44Gflops isn't really stable - I can open up a few programs in Windows and drop my efficiency down to have LinX pass with a few notches lower voltage. You might want to look into that.

[OC Nub]

Nice job ziggo0. Are you the same ziggo I played in COD4?

[KURTZ]

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http://valid.canardpc.com/show_oc.php?id=1507562

not bad ...

[Oztopher]

MUCH better getting more gflops than i do now

How did you do it in the end kurtz?

[KURTZ]

MUCH better getting more gflops than i do now

How did you do it in the end kurtz?

simply! load defaults onto the mobo's BIOS .... I think it is still immature ... need a bettere release ...

however i think that this chip is amazing ... maybe the better in the business ...

[Oztopher]

AHh i see. yes, it's a good chip

[MikelMolto]

@KURTZ
Nice CPU. Low VCore for 4Ghz.
If You are looking for GFlops in LinX, then try with deactivated HT. You will be surprised!

[KURTZ]

@KURTZ
Nice CPU. Low VCore for 4Ghz.
If You are looking for GFlops in LinX, then try with deactivated HT. You will be surprised!

i know it Mike ... anyway i tried with C1E enabled and disabled ... if i disable the C1E my gflops drop down ... really weird ...

231 BCLK!!!!

[KURTZ]

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my first under 9sec score ... w/HT enabled ...

[tonus]

CPU clock drive=700mv
PCIE clock drive=700 mv = stable overclock to me

CPU clock drive=800mv
PCIE clock drive=900 mv = my system is not stable and need to increase Vcore.
Is this normal.

[Oztopher]

Thought i would post this, as i reckon the DRAM speed was pretty awesome for a stable overclock:




Now the question is, is this worth leaving on 24/7? 1.64v isn't exactly a dangerous level and i'm pretty sure it's damn stable. Should i just knock it down and leave it at 1900mhz 7-9-8-24 (1.57v), and call it a day? Bare in mind i would be using this for crunching.

@tonus, to be honest i reckon you should just use 800mv and 900mv, as those are the default settings. See what you can get out of that.