A Tale of Two i7 920s

My second i7 920 arrived yesterday, so I popped it into the Asus P6T MB to see how it compared to my previous i7. It turns out that it is very similar in overclocking abilities. The first would prime fine @ 192 x 21 (turbo enabled). The second will prime fine @ 191 x 21 (turbo enabled). Seeking the bragging and marketing rights of 4Ghz, I endeavor to get the second 920 up to 192 BLCK as well but so far have not been successful. Here's what I've tried so far:
Asus P6T settings:
BLCK: 192
Dram feq: 1539 (works fine w my 3 Corsair Dominator chips)
CPU voltage: Edit: 1.35V
CPU PLL 1.96
QPI/Dram Core volts: 1.35
Dram bus voltage: 1.66
CPU Differential Amplitude: 800mV

These settings work great with CPU #1, but I get BSOD with CPU #2 after a few minutes of Prime 95. I increased both CPU votage and QPI Dram volts to 3.75 and tried again, but received BSOD after many more minutes.

Conclusion: I might be able to bump my BLCK from 191 to 192 on cpu #2 if I keep tweaking, but it's too much effort for too little gain. I've found that these i7 920s overclock easily to a certain number and then don't really want to go much beyond that number.

The good news: I've never seen a miscalculation in Prime95. The i7s seem to either run reliably or BSOD.

Your thoughts?

PS: I'm getting an EVGA x58 MB on Monday and will continue the comparison. Perhaps the chips will overclock slightly differently on the new MB.

Papafox said:

CPU voltage: 3.5

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I'm sure you mean 1.35?

Thanks Oldskool, I'll correct and make an edit note

PS: I just did some calculations and 191 x 21 is over 4Ghz, so I'm good with CPU #2. Nonetheless, if someone knows an easy way to get higher I'm all ears.

Papafox said:

PS: I just did some calculations and 191 x 21 is over 4Ghz, so I'm good with CPU #2. Nonetheless, if someone knows an easy way to get higher I'm all ears.

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Did you try higher uncore voltage? My i7 doesnt like as low as 1.35v, cant even do 175 then. At 1.54v it is prime stable at bclk 200.

What is the max qpi/vtt voltage?

For 200 BCLK i use like 1.28 or so, if I want to get 205 BCLK I have to up it to like 1.64. Right now I am at 210 abd I am using 1.77. Yeah, I know, chip is going to die soon!!!

Oh, that voltage is too high, I have to start lowering and find a stable one.

Try upping your BCLK to 200 mhz and your core volts to 1.430. easiest way to get 4.2 out of your chip

More voltage you three say. I can try more core volts and uncore, but I'm air cooled and after an hour with Prime95 I'm at 74 degrees on those cores. Seems like I'd fry an egg at 1.5. I've upped both volts to 1.368 a few hours ago and it looks good for 190 or 191. I'll try Jasonelmore's 200BLCK and 1.43 volts.

The Asus P6T Northbridge is another issue. I sometimes get a BSOD after an hour of Prime95, and I think the problem is the northbridge overheating. As I write I have a fan going on the test bench, pointed down at the northbridge, but of course most of that air gets sucked into the fan for my True120. It's been about an hour and a half with no probs, so I may have found the culprit. Maybe I ought to turn the TRUE120 90 degrees so that I can get fan air directly on the northbridge. I'll try a few things and report back. Thx!

is the i7 really worth upgrading my system? right now i have a QX9650 and 8gigs of ddr2 in a p5k premium black pearl ... i've got 4Ghz easy on this thing and my supi time is just over 11 secs

i do render a lot of video / special effects and i'm going to be opening a business that requires a good render machine for video editing as well as a good ammount of ram i'm afraid 3 gigs wouldn't be enough for me so i'd have to spend another 200 bucks or so on a 2nd tri channel kit

selling all my parts now wold probably put me at $790-800 bucksfor that i figure i can get

920 - $300
Rampage extreme II - $400
patriot viper 6gb tri channel kit - $250
and an 4850 for about - $100

totaling about $250 bucks out of pocket for 2 gigs less and an i7 or $500 for 12 gigs and an i7

Dapper Dan,
It all depends upon how much rendering you do. The i7 is definitely faster than the Penryn Quads at rendering. In Cinebench you're talking a score of about 19K for the i7 vs. 13.8K for a QX9770, so you'd have to make the judgement. You would probably be best off waiting for i7 system prices to fall a bit, and maybe a new stepping to make it just that much more attractive.

For me the decision was easy because i7 is head and shoulders better at Microsoft Flight Sim X than previous generation quads, and that's the program I run when I really need CPU power.
Papafox


To the others:
I am quite happy with the 50% overclock I have achieved with this 920 chip, and I feel no need to get another 5% speed in return for the effort, heat, and wear and tear. Thanks all for the suggestions. By adding a little voltage to both CPU core and uncore I was able to get the 191 or 192 BLCK running okay. Cooling of the Asus P6T northbridge was indeed an issue. jasonelmore, my weaker 920 couldn't pull off 200 BLCK & 20 multiplier @ 1.43v, I bet my stronger 920 could, but I'm content with my 192 BLCK now, so there's no need for me to press further. I would have to improve my cooling to go higher, and that's too much hassle right now. Cheers.

Sophisticated,
I must admit that i7 Nehalems and water cooling is at present a good match. I'm reconsidering but would prefer to avoid the expense and effort. Next year, when the 32nm i7s come out, air will make more sense again. If I can just stumble through this year then the water-cooling might not be necessary.

Dapper Dan said:

is the i7 really worth upgrading my system? right now i have a QX9650 and 8gigs of ddr2 in a p5k premium black pearl ... i've got 4Ghz easy on this thing and my supi time is just over 11 secs

i do render a lot of video / special effects and i'm going to be opening a business that requires a good render machine for video editing as well as a good ammount of ram i'm afraid 3 gigs wouldn't be enough for me so i'd have to spend another 200 bucks or so on a 2nd tri channel kit

selling all my parts now wold probably put me at $790-800 bucksfor that i figure i can get

920 - $300
Rampage extreme II - $400
patriot viper 6gb tri channel kit - $250
and an 4850 for about - $100

totaling about $250 bucks out of pocket for 2 gigs less and an i7 or $500 for 12 gigs and an i7

Click to expand...

A business where the computer would be an actual investment and time=money? Probabyl worth it. You just might want to wait until you find yourself needing more compute speed is all, like when the current one running 24/7 can't keep up with demand.

well ... i've done cinebench on my QX9650 stable at 4.341Ghz got 18371 , haven't tried 4.3 stable for hours but i have had 4.05Ghz stable at 2.5 hours which i don't think would be much less than 18317 in cinebench and i don't plan on rendering for 2.5 straight hours ever ... the MOST i have done thus far is maybe an hour,little bit more perhaps.