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I7 920 D0 @ 3.8 Ghz unstable and crashing with prime95

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January 7, 2010 2:14:40 AM

Well, I tried to overclock my i7 to 3.8 Ghz the last night and it just kept crashing... Im running my i7 @ 3.4 Ghz with this setting at the moment :

RAM Timings : 8-8-8-24
BLCK : 170
CPU Clock ratio : 20 X
Cpu Vcore : 1.13125V
QPI / Vtt Voltage :1.2000V
CPU PLL : 1700V
DRAM Voltage : 1.500V
Turbo : On
HT : On
C3/C6/C7 : Disabled
Memory multiplier : Auto

My PC stats are :
EX58 UD3R Gigabyte
i7 920 D0
Cooler master V8
Nvidia Geforce9400GT
Kingston 1333 Mhz

My settings after Overclock to 3.8 Ghz
BLCK : 190
CPU Clock ratio : 20 X
Cpu Vcore 1.275V
QPI / Vtt Voltage : 1.400V
CPU PLL : 1.800V
DRAM Voltage : 1.500V
Turbo : On
HT : On
C3/C6/C7 : Disabled

Yes i know theres alot of guides but i cant find any guide for i7 920 d0
this is my second overclock and im really noob at this ... so heres the questions

I saw in few forums people running i7 920 @ 3.8 Ghz with Vcore 1.200V, I tried it and my PC still kept crashing with prime95 with large fft test..why?(Heres the guy runnning i7 920 @ 3.8 Ghz with 1.2V with 38-42C temps idle aircooling http://www.youtube.com/watch?v=3Uh7vjuFWdI i know his fan is better than v8 but still, how is he running @ 3.8 ghz without crash.

Do i have to raise other voltages? QPI /Vtt? CPU PLL? Ram? Ram timings?

My i7 920 D0 @ 3.4 Ghz is currently running at 36C-40C idle well heres my temps http://i48.tinypic.com/2vseqtt.jpg
Theres something weird in this pic... after i set everything back to 3.4 Ghz and i run cpuz it says 3568.8 Ghz and x21.0 multiplier and the bios says 3.4 Ghz with x20 multiplier after i set everything back to 3.4 ghz...whys that?

What are the settings for 3.8 Ghz with i7 d0?

Im running my ram @ 1360 Mhz with 170 blck setting and my ram is only 1333 Mhz, is it bad? what will happen if i run it at 1500? it will burn only burn my ram or it will damage my motherboard/cpu?


Sorry for asking so many questions and as you can see english isnt my first language i learned it all through an online game and thaks for answering so fast in this forum really helpful :) 
January 7, 2010 2:31:07 AM

The i-7 has "turbo boost" which effectively adds one multiplier turning your i-7's base x20 into x21. If you have turbo boost turned on in the bios this is why your multiplier is different. Please check out Overshocked's guide I'm linking below, and drop him a thank you if it helps you.

Click this one:
http://www.tomshardware.com/forum/256021-29-core-overcl...
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January 7, 2010 2:33:27 AM

That Vcore looks a bit low, but I haven't overclocked a 920. The people listing their voltages are probably saying their voltages on load (after vdrop). A voltage of 1.375 is what Intel recommends as your max, and 45nm processors are more sensitive to voltage changes than 65nm, so I wouldn't go much over that even if only for a little while.

Your changing cpu speeds seem to be caused by having Turbo on. It is probably adjusting base on the processor load. In bios it should be very low, so it lowers the multiplier.

I think you should try raising your processor's voltage a bit and overclock slowly, because it seems like you rushed into the 3.8 ghz and tried to just follow guides. Remember, every processor is different. Yours might just not be as well made as some others.

On your question about your ram. I would run it on stock speeds or lower for now, to make sure your ram is not what is crashing your system. After you can get a stable oc you like, you can slowly change your multiplier to increase your ram speed until it is unstable. You could always increase the voltage on your ram too, but I don't see much need. The speed of your ram has a very very small impact on the majority of the things you do on a computer, including gaming.
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January 7, 2010 2:34:19 AM

Also here is the i7 guide and what stepping you have doesn't matter the basic concept is still the same.

http://www.tomshardware.com/forum/253365-29-core-overcl...


If you are having problems with stability when OC'd to 3.8GHz you should try it with Turbo off as that could be the problem as well and it isn't really recommended to have that on when the system is OC'd.
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January 7, 2010 2:41:29 AM

I already saw overshocked's thread already, it only answer some of my questions not all x_x yea im about to turn the turbo off, after i oc'd to 3.8 ghz i had to clear the CMOS and all my settings resetted to default @ 2.66 Ghz i guess turbo was off even tho i think it was on brb .. can anyone tell me the voltages? or answer some of my questions? :[
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January 7, 2010 2:53:00 AM

Well i had turbo off when it crashed alot of times at 3.8 Ghz ... im going crazy this is pissing me off i raised my voltage till 1.3 V when i OC'd @ 3.8, and im running really stable @ 3.4 ghz with 1.13125V
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January 7, 2010 3:19:18 AM

Pretty sure we answered all of your questions as definitively as possible. No, we can not tell you what exact voltages every single piece of hardware needs to be used at and what settings to use for a certain fsb speed. We can suggest basic voltage increases based on your description. I recommend increasing your cpu voltage, as I stated in my previous reply.

I would stay at 3.4 ghz unless you actually need more speed. The voltage increase you require seems a bit high for the performance benefit.
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January 7, 2010 5:26:33 AM

Well i just want to know what will happen if i run my kingston 1333 mhz at 1400 mhz?
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January 7, 2010 7:01:38 AM

You'll see little to no benifit in performance and it won't help your stability problems. Before when you had Turbo enabled it was a bit like you were trying to get 4ghz stable (3.8 + 0.2 Turbo = 4ghz)

Personally I need 1.265xx Vcore to be stable at 4ghz (HT enabled) so your Vcore is alittle low i think, but as already stated we can't give you precise voltages because every chip is different.
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