i have an i7 920, p6x58 mobo, 12gb dominator ram, H50 and gtx 470 rig.
i oc'ed to 4 Ghz no problem some time ago. Now the system simply doesn't start if i try to oc even at minimum values... any clue what it might be?
I just turned x.m.p. on in the bios and set the blk value. I read that this was the most effective way to perform a stable oc.
To put the cpu running at 4.0Ghz I set the blk value to 190, but now even if I just set it 10 unit up that the default it just doesn't start up. It doesn't even gives that initial "beep". And sometimes it lits the MemOK led. I thought it could be some memory stick that went off but I already tested every one one at a time.
That probably means your initial overclock wasn't really stable and something or things got irritated. Did you clear the cmos? You can most likely save your overclock profile, then clear the cmos. Then you can go back and work on what went wrong.
On another note... Are you watching other temperatures within the case? That h50 takes away the ability to cool around the cpu socket. NB temps, HD, etc.
You may want to "Google" i7 920 overclocking guide, should be a couple hundred out there. Look for one's that will explain what the Bios entries are for and what to turn off to start with. It should also explain what programs are best for testing and monitoring when you overclock. If you find one that says just put these settings in your Bios, keep looking. Start from scratch and don't leave many settings on AUTO.
If it still won't let you overclock at all, you've damaged something.
You'll want to start with your target baseclock and stress test it to find the lowest QPI voltage that still passes the tests while you keep the RAM and CPU on low multipliers. You then overclock your RAM and find the lowest voltage (or use the rated values, just make sure the QPI and RAM voltages are within half a volt of one another). After all that is stable, you set the CPU multiplier to match what you were looking for and then find the lowest stable voltage. After that's done, you can turn the power saving settings back on in order to lower your CPU multiplier, voltage, and temp while it isn't under load.
If it just won't run stable at higher clocks even with a lot of juice (1.35+ volts), then that probably means your CPU was running on very high voltages up until now and will have to stay at lower clocks is all.
Check your temp with Everest or Coretemp or CPUID's HWMonitor. Perhaps some components get too hot. Also, anything should not be set to Auto whenever you OC. Auto setting is not reliable, sometimes even damaging components.
You XMP profile was clocking your memory at the right speed, then you upping the BCLK gave it another kick of super instable OC. You should download the memory multiplier after the XMP profile. BCLK x memory multiplier = memory speed. Memory can't exceed their rated speed by much.
To overclock you need higher Vcore voltage too. 4Ghz should be attainable with sufficient cooling. The average voltage for 4Ghz with an i7 920 should be around 1.25v-1.35v. Do not exceed 1.4v, otherwise you can damage the processor.
The H50 won't get good temperatures. Though corsair advertise it as watercooling because it has a drop of water in it. Its performance is mixed into the air cooling bunch. Even corsair was showing the H50 getting 80C-90C under stress test, a temperature I personally won't want to run at.
I recommend something around 3.8Ghz, Its a much more efficient overclock. Most i7s can do that with very little voltage increase. Around 1.15V -1.25V is average for this clock. Such a big difference in voltage for just 5% difference in performance.