Core i-920 C0/C1: 3.8 GHz overclock freezes but only with Prime95 - does it matter?

Darren Hodgson

I've been running my Core i7-920 @ 3.6 GHz for several months now with 100% stability using at first a BLCK of 180 MHz, a multiplier of 20x, a VCORE of 1.28750 V and a QPI/DRAM Voltage of 1.3 V then the same voltages but with a BCLK of 200 MHz and a multiplier of 18x due to having upgraded my memory from 6 GB of 1,333 MHz to 12 GB of 1,600 MHz G.Skill Ripjaws (the RAM requires only 1.5 V at its recommended 1,600 MHz speed and that is set manually in the BIOS). Load temperatures never exceeded 65 C during Acronis backups (the only application that stresses all eight cores to 1005) and gaming.

So I figured I'd push my Core i7-920 a little further on the same voltages by setting the multiplier to 19x to give a 3.8 GHz overclock and to my surprised it appeared to be stable. I ran Heaven 3.0 on maxed settings at 1920x1200 for 40 minutes without issue and 3DMark11 was fine as were the handful of games I tested. Feeling confident, I ran Prime95 v27.4 64-bit's default test but my PC appeared to freeze after 25 minutes during Test 8. The screen froze there was no error message or blue screen unfortunately.

Seeing as Prime95 pushes the PC to extremes that software doesn't, does it really matter when everything else appears to be fine? Obviously, my PC is not 100% stable in stress testing but does appear to be fine under normal use, even when I max all eight threads to 100% to using the MaxCPU tool.

I have bumped the VCORE up a little to 1.2950 V though and set the CPU PLL manually to 1.84 V for now and so far my PC has been stable. However, I have not ran Prime95 again.

Comments?

WhiteLightning · 04-27-2012, 13:56 | posts: 20,495 | Location: Netherlands

yes you need to be prime stable, i would also try ibt or linx or some other program. you might not get a bsod straight away, but its too damn annoying you get one while your in a game doing your best and it crashes.

Mr_Alexander · 04-27-2012, 18:16 | posts: 1,602 | Location: TORONTO, CANADA

I also have i7 920 CO. I have it stable at 3.6 and could not go any higher. No matter what I tried I could not pass 3.6. and have it stable. So finally I let it go.

Veteran · 04-27-2012, 23:11 | posts: 7,405 | Location: United kingdom

I had a 920 c0 in 2008 before my 930,i managed to get it to 3.8 with ht on,no matter what i did i couldnt get ot to go past this on a TRUE cooler,they dont oc that well but 3.8 is till good for one of these.

Darren if your getting problems then up your vcore,if its getting too hot then decrease your oc lower than 3.6 or get better cooling,thats your only option with that chip if you want to be stable.

xaudiox · 04-28-2012, 18:04 | posts: 145 | Location: UK

My way of thinking is whatever stress test gives you errors (ie prime95) then you need to get stable with that program.

In my case prime,linx,occt run for ever and IBT gives me errors so i always get stable with IBT.

Every computer is different.

Terminator1000 · 04-28-2012, 19:35 | posts: 291 | Location: Detroit, MI

I had a Intel 920 D0 and i ran it rock solid at 3.6GHz for the longest time. It was at stock voltage actually, i think i really got a hell of a 920. But ya, if i was failing on ANY test, id make sure i became stable. I mean yeah, on some software you might be fine, but in the end, your technically pushing the CPU beyond stable specs in some areas if its ok doing this, but not ok doing that.

So i would definitely fine tune it so its 100% stable everywhere.

Darren Hodgson · 04-30-2012, 14:56 | posts: 9,746 | Location: England

Well I've been using my PC as I normally would with the current 3.8 GHz setting for games (Binary Domain mostly but also The Witcher 2 EE and Ridge Racer Unbounded), listening to music and browsing. I did an Acronis True Image 2011 image of my C: drive over the weekend; the only application I use that stresses all 8 threads 100% for up to 30 minutes while it does the backup. It has been 100% stable so I think I'm going leave the settings as they are. I personally don't think stress testing with Prime95 or IBT is worthwhile when nothing I use would ever push my PC to those extremes. I was stable for over six months at 3.6 GHz and I never ran Prime95 or IBT for that either.

killer_939 · 04-30-2012, 15:13 | posts: 2,565 | Location: Australia

Funny, my computer can pass prime overnight very easy but still bsod randomly through the week unless i give it more cpu voltage. I can pass prime 95 at 4.7GHz +0.03v offset but i run 4.6GHz +0.05v offset so it is reliable lol. I would make sure if i was you that my system could pass it tho.

Darren Hodgson · 05-01-2012, 08:08 | posts: 9,746 | Location: England

Nah, I'm seriously not that bothered. If my PC does crash at some point during a stressful game or whatnot then I'll look into raising the voltages, etc., depending on the error message or whatever. A freeze would definitely indicate a voltage problem. I don't use my PC for anything other than recreation so it doesn't need to be 100% guaranteed stable, just stable enough to run games. Which it appears it is at the moment.