In the last month, I purchased three Intel i7 920 CPU's with the intention of keeping the one that OC'ed the best. My initial X58 motherboard was the Gigabyte EX58 Extreme and I had so many problems with those boards that I couldn't individually test each CPU. I RMA'ed both of the Gigabyte boards back and got an open box ASUS P6T Deluxe, which has been so much better. So without a wonky mobo to worry about, I was able to start sorting out the CPU's and the results were fairly interesting (full system specs are in my signature).
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i7 920 #1 (Purchased from Mwave on the week of its launch for $310 plus tax. Batch #3836A866 and pack date of 11/06/08.):
24/7 Prime95 Stable OC: 3.8GHz (20x190) @ 1.2875v. (CoreTemps) Idle temps = 36 - 40*c, Prime95 small FFT load temps = 70 - 76*c.
Highest OC tested: 4.0GHz @ >1.4250v. Idle temps = 45 - 50*c, load temps = 86 - 90*C AND NOT PRIME95 STABLE
Summary: this CPU was the earliest pack date and got to 3.6GHz with no effort. 3.8GHz was the sweet spot because BIOS vCore was relatively low at 1.2875v and idle temps were decent. At all speeds, load temps were always higher than I like to see but at 4.0GHz getting near and sometimes over 90* was very disturbing for me. The increase in voltage it needed to get from 3.8GHz to 4.0GHz was substantial (over 0.15v) with ridiculously hot temps and was definitely not worth it for me. And even then, it still wasn't Prime stable. I wasn't going to give it more voltage when temps were into the 90's as is!
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i7 920 #2 (Purchased from Fry's on 1/2/09 for $229.99 plus tax. Batch #3839A577 and pack date of 11/25/08.):
24/7 Prime95 Stable OC: 3.6GHz (20x180) @ 1.4000v. Idle temps = 33 - 36*c, Prime95 small FFT load temps = 63 - 67*c.
Highest OC tested: 3.8GHz (20x190) @ 1.500v!!! Prime95 hangs within 10 seconds of start. Could not boot at 4.0GHz at all even at 1.5500v!
Summary: When I took out the original 920, I went with this CPU next because it had the latest pack date and I thought that MAYBE newer is better??? WRONG!!! Since the mobo BIOS was set from original CPU above (1.2875v vCore and 20x190) I just booted this CPU at those settings. Nothing. Upped the voltage to 1.3000 then 1.3250 then 1.3500v . . . and still nothing! I thought I broke the motherboard somehow on the swap!!! When 1.4000v still wouldn't boot, I loaded defaults and it finally booted. Many trials and reboots later, I discovered that the highest BCLK this CPU would reliably boot into Windows with is 180. It took 1.325v just to boot at 3.6GHz and needed 1.4000v to become Prime stable at 3.6GHz (920 #1 only needed 1.2875v for 3.8GHz stable). It took 1.5000v just to get the CPU to boot at 3.8GHz but at this speed it was totally useless as Prime95 froze immediately each time. 4.0GHz was never reached; I stopped at 1.5500v and did not want to get into the 1.6000v range.
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i7 920 #3 (Purchased from Microcenter just before Christmas for $249.99 plus tax (later price adjusted to match Fry's price above). Batch #3838A819 and pack date of 11/13/08.):
24/7 Prime95 Stable OC: 4.005GHz (19x211) @ 1.4000v. Idle temps = 32 - 37*c, Prime95 small FFT load temps = 73 - 80*c.
Highest OC tested: work in progress (hope to get to at least 4.2GHz or ???)
Summary: Luckily, third time was in fact a charm! I started this CPU out at the known stable settings for CPU #1 and it booted and was Prime stable @ 3.8GHz & 1.2875v with no problems. 4.0GHz took 1.4000v but would not be Prime stable at 20x200 so I had to go 19x211 (I've read that you can do 19x211 for 4.0GHz at lower voltages than 20x200 so I'll see if I can back down the voltage a bit later on). This is the first and only 920 that I've successfully gotten to be stable at 4.0GHz and the idle/load temps are still acceptable for this speed so I'll try to push it to 4.2GHz (or more) and update if successful.
The really cool thing about this CPU is that I ALMOST returned it to Microcenter because I did pick up 920 #2 for a lower price at Fry's. But as I stood there at the return counter, I decided at the last second to keep it if the would price match Fry's price. Luckily they did and I got my keeper CPU!!! Phew!
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Pretty interesting how three 920's manufactured within three weeks of each other can each have different "personalities"!!! Probably most impressive is that this is done with 6x2GB Corsair Dominator DDR3 running at 1693MHz (93MHz over their rated speed). I had read that the ASUS boards had problems with 12GB but looks like BIOS 1102 might have resolved this???
Now it's time to go dump two 920's on ebay!!!
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i7 920 #1 (Purchased from Mwave on the week of its launch for $310 plus tax. Batch #3836A866 and pack date of 11/06/08.):
24/7 Prime95 Stable OC: 3.8GHz (20x190) @ 1.2875v. (CoreTemps) Idle temps = 36 - 40*c, Prime95 small FFT load temps = 70 - 76*c.
Highest OC tested: 4.0GHz @ >1.4250v. Idle temps = 45 - 50*c, load temps = 86 - 90*C AND NOT PRIME95 STABLE
Summary: this CPU was the earliest pack date and got to 3.6GHz with no effort. 3.8GHz was the sweet spot because BIOS vCore was relatively low at 1.2875v and idle temps were decent. At all speeds, load temps were always higher than I like to see but at 4.0GHz getting near and sometimes over 90* was very disturbing for me. The increase in voltage it needed to get from 3.8GHz to 4.0GHz was substantial (over 0.15v) with ridiculously hot temps and was definitely not worth it for me. And even then, it still wasn't Prime stable. I wasn't going to give it more voltage when temps were into the 90's as is!
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i7 920 #2 (Purchased from Fry's on 1/2/09 for $229.99 plus tax. Batch #3839A577 and pack date of 11/25/08.):
24/7 Prime95 Stable OC: 3.6GHz (20x180) @ 1.4000v. Idle temps = 33 - 36*c, Prime95 small FFT load temps = 63 - 67*c.
Highest OC tested: 3.8GHz (20x190) @ 1.500v!!! Prime95 hangs within 10 seconds of start. Could not boot at 4.0GHz at all even at 1.5500v!
Summary: When I took out the original 920, I went with this CPU next because it had the latest pack date and I thought that MAYBE newer is better??? WRONG!!! Since the mobo BIOS was set from original CPU above (1.2875v vCore and 20x190) I just booted this CPU at those settings. Nothing. Upped the voltage to 1.3000 then 1.3250 then 1.3500v . . . and still nothing! I thought I broke the motherboard somehow on the swap!!! When 1.4000v still wouldn't boot, I loaded defaults and it finally booted. Many trials and reboots later, I discovered that the highest BCLK this CPU would reliably boot into Windows with is 180. It took 1.325v just to boot at 3.6GHz and needed 1.4000v to become Prime stable at 3.6GHz (920 #1 only needed 1.2875v for 3.8GHz stable). It took 1.5000v just to get the CPU to boot at 3.8GHz but at this speed it was totally useless as Prime95 froze immediately each time. 4.0GHz was never reached; I stopped at 1.5500v and did not want to get into the 1.6000v range.
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i7 920 #3 (Purchased from Microcenter just before Christmas for $249.99 plus tax (later price adjusted to match Fry's price above). Batch #3838A819 and pack date of 11/13/08.):
24/7 Prime95 Stable OC: 4.005GHz (19x211) @ 1.4000v. Idle temps = 32 - 37*c, Prime95 small FFT load temps = 73 - 80*c.
Highest OC tested: work in progress (hope to get to at least 4.2GHz or ???)
Summary: Luckily, third time was in fact a charm! I started this CPU out at the known stable settings for CPU #1 and it booted and was Prime stable @ 3.8GHz & 1.2875v with no problems. 4.0GHz took 1.4000v but would not be Prime stable at 20x200 so I had to go 19x211 (I've read that you can do 19x211 for 4.0GHz at lower voltages than 20x200 so I'll see if I can back down the voltage a bit later on). This is the first and only 920 that I've successfully gotten to be stable at 4.0GHz and the idle/load temps are still acceptable for this speed so I'll try to push it to 4.2GHz (or more) and update if successful.
The really cool thing about this CPU is that I ALMOST returned it to Microcenter because I did pick up 920 #2 for a lower price at Fry's. But as I stood there at the return counter, I decided at the last second to keep it if the would price match Fry's price. Luckily they did and I got my keeper CPU!!! Phew!
----------------------------------------------------------------------------------
Pretty interesting how three 920's manufactured within three weeks of each other can each have different "personalities"!!! Probably most impressive is that this is done with 6x2GB Corsair Dominator DDR3 running at 1693MHz (93MHz over their rated speed). I had read that the ASUS boards had problems with 12GB but looks like BIOS 1102 might have resolved this???
Now it's time to go dump two 920's on ebay!!!