Overclocked System Crashes When Stress Testing


I have a problem with my overclocked system, and I would appreciate if you could help me solving it.

When I overclocked my Intel i7 920 processor today, it suddenly crashed after 2-3 minutes of stress testing it with "Everest Ultimate edition". I was monitoring the load of the CPU as well as the temperatures of the CPU as a whole but each Core individually, but I did not notice any abnomalies throughout the process until my screen suddenly went pixly and my speakers making buzzy noises for about 1-2 seconds, it then rebooted.

My Computer is quite new - just 2 months old and it is pretty much a Hi-End PC.
Here are my system specs:

CPU: Intel i7 920 @ 2,66 GHz (overclocked to 3,33 GHz)
CPU Cooler: Zalman CNPS10x Extreme
Motherboard: Asus P6T
PSU: 850 Watts (I know... it's way too much than needed)
Graphics Card: ATI HD5770
Memory: 3x DDR3 2GB @ 1333 MHz (Overclocked to 1403 MHz)
HDDs: 1x Velociraptor 300 GB (@ 10k RPM), & 1x 500 GB (@ 7,2k RPM)

--- --- --- ---

Here is what I modified in the "AI Tweaks" menu in my BIOS:

CPU Ratio: 19.0
BLCK: 175
PCIE Freq: 100
DRAM Freq: 1403
UCLK: 2807
QPI Link: 6316 MT/s
CPU Voltage: 1,28750
CPU PPL: 1,84
QPI/DRAM: 1,28750
IOH Voltage: 1,10
ICH Voltage: 1,20
DRAM Voltage: 1,64

What is causing this instability of my system when overclocking it? Everest notified me of critical tempratures of CPU when stress testing it on 3,33 GHz (max temperature noted was 64 degrees C about 108 degrees F). Should it not be able to handle higher temperatures?

I'd appreciate if you could help me solving this problem, as well as posting what values I should put for each setting in BIOS. I am interested in testing 3,33 GHz and 3,6 GHz.

Thank you in advance,

PS: System Stablitity comes first ... I am not interested in achieving über-clockspeeds such as 4,1 GHz ... or anything higher than about 3,6 GHz for that matter
10 answers Last reply
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  1. You are overlooking a fundamental reality of overclocking in that not all systems are created equal so no one can tell you what precise values to enter that will guarantee you a stable system

    My suggestion is read the OC guides for your processor and experiment.

    Sometimes if you get lucky you may be able to run across settings offered up by someone who has almost identical equipment and you can use it as a sort of guideline or starting point but still no assurances.

    I have two identical hardware i7's yet one is quite happy with 1.15V on the CPU while the other requires 1.26V to attain stability.

    Read and carefully experiment is the best most of us can do.

    Oh and I would add to that know your hardware such as memory specifications.

  2. I see.... I don't like experimenting, but I guess it's the only way, lol.

    Oh, and yes - I have come across many overclocking guides for the i7 920 on the internet, but none of the guides have similar values enough. I mean some have the CPU voltage set to 1,35 while others to 1,6 for example.

    I guess I'll have to "play" with the values of the CPU voltage then to see what is most suitable for my system... But I guess the voltages is the only thing that *can* make a PC unstable, correct? I mean, pushing the frequency values just a little, can't be the (main) reason for system instablity. Correct?

    Oh, and thanks for the link.
    I will read the guide and see what I can do.

    Thank you for your reply.

    PS: is 64 degrees C as tops an acceptable temperature for stressing the i7 920 @ 3,33 GHz?
  3. I finaly found the perfect overclocking guide I was looking for.

    I thought that I'll post it here so that anyone that wants to overclock his/her i7 can have a look.

    This guide uses the i7 920 (2,66 GHz) with the ASUS P6T motherboard:


    It really is a SUPER guide... worked flawlessly when I tried.
  4. Quote:

    Thank you for your reply.

    PS: is 64 degrees C as tops an acceptable temperature for stressing the i7 920 @ 3,33 GHz?

    You're welcome.

    Temperature isn't particularly great for 3.33GHz but it's not bad either. It does tend to come down to the luck of the draw on the CPU itself as well as what cooling solution you are using and in what case.

    I'm assuming that is core temps that you posted right?
  5. Well, the temperatures are actually not that accurate anymore, because in my earlier tries of overclocking, I came across a guide that suggested that the CPU ratio should be 19.0 instead of 21 that I have now.
    This meant that I had to increase the BLCK Frequency to 200 to achieve 3800 MHz with a CPU Ratio of 19.0 (200 x 19). Now that the CPU Ratio is 21, the BCLK Frequency is set to only 181, but I still achive 3,8 GHz (21 x 181 = 3801 MHz).

    As for that reason the CPU core temperatures on stress did not exceed 60-62 degrees C. It's quite a difference since the core temperatures before reached up to 66 degrees C, on 3333 MHz. Now the temps do not pass 62 degrees C, and that is on 3,8 GHz!!
  6. and yes... it's the cre temps I am talking about.

    PS: Temperatures on idle are around 34-38 degrees C
  7. 60C - 62C at 3.8GHz setting under full load is a decent temperature.

    I can't get my temps that low under full load @ 3.8GHz as they are in the high sixties.
  8. I see... I wonder though what made my PC so unstable before... I even max-ed the CPU Voltage, but it did not help... I suspect that my RAM memories could not be overclocked too much or something... they are only on 1333 MHz...

    But I must say that even with almost 90% faster cpu speed, I dont notice any remarkable difference in boot, or anything. I think I am going to buy another Velociraptor to pair it with my other raptor so I can go RAID 0... Or maybe I'll wait though until SSDs become cheaper so I can make RAID with 2 SSDs instead...
    I want my PC turbo charged! hehe...

    By the way, have a look on this youtube video... this inspired me to go RAID 0:
  9. If you are looking to see a marked improvement in boot times then yes you would need to go with SSD's.

    Instability is often a result of memory settings.
  10. Okay, thank you very much for your help. :-)
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