Haswell overclock works, then doesn't

teppic

teppic

teppic

Soldato
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25 Jun 2013
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I've been running my Haswell set up at 4.3GHz / 1.23v without any problems, though I've not done serious stress testing (it's been fine in games, etc.).

I decided to run Seti@Home for a bit. It was fine running for a few hours, results were validated and there were no problems. Then when I later booted the computer was locking up or crashing. I've tried reducing the OC to 4.2GHz and increasing the voltage to 1.25v and it still locks up within seconds of Seti@Home starting.

I've got it now back on stock settings, and it's running fine.

I can't understand what's happened. Can a CPU start to fail an overclock this quickly?
 
seti@home is a bit like prime95 - I had it running for about 6 hours at 4.3GHz/1.23v. The PC is now crashing within 3-4 seconds at 4.2GHz/1.25v.
 
I've just reinstalled it to check that. I'll try putting up the clock speed back to 4.2GHz/1.25v. I'd have expected the app to crash though rather than the PC if it weren't an OC issue.

edit: Trying 1.235v and 4GHz for now, it's stable but my temps are really high. Could it be the TIM?
 
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It was getting to 90C. Dropping it to 1.2v and running at 4GHz is working at the moment, temps around 76-80C.
 
It's MX-4. I intend to replace the cooler with my decent one soon, at the moment it's a cheaper one - but like I say, it was running fine before. It's all new stuff and completely dust free.
 
Something's screwed. It was working, then powered off. Switch on - it gets to the UEFI splash screen and shuts down. Tried clearing the CMOS, it gets to the same place, says it has reset to defaults, then powers off. Start up again, no change.
 
It gets to where it should start to boot then powers off completely. The CMOS has been cleared though - it says that before it powers off.
 
Yeah, just tried the backup BIOS and it works. Switched it back and it's working ok now.

This is all weird. I think the board may be faulty.
 
It's a stable BIOS release though. Everything was working fine, then overclocking went funny earlier. It was only at 4GHz when it powered off - which is a very low OC.
 
It's just that the board has inexplicably become worse at overclocking and it powered off for no reason. I've not flashed the BIOS so it looks like it became corrupt when it powered off. I'll see how it goes, but something seems up to me.
 
It was running ok, but the same happened again. Powered off and wouldn't start beyond the UEFI screen. Flicking the BIOS back fixed it again.

Pretty sure the board is faulty now.

Now my CPU is showing 100% throttling at 35C and won't go above 800MHz.

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Yup. I was getting the no-start problem again. I reset the BIOS, started up and noticed it seemed really slow.

I've taken out the graphics card, reset it again, it's still booting up with 100% throttling at 800MHz.
 
It reads A0 when it gets to Windows, but it's still stuck at 800MHz, and when it powers off it won't start again. I didn't reflash the BIOS, but the board has two BIOSes, the original is untouched.
 
I tried a second CPU in the board, exact same result. The other BIOS can't be corrupt as I've never used it, it's the BIOS that shipped with the board and you have to flick a switch to enable it.
 
I can reflash it, but it seems a bit pointless when the BIOS I've never used before is showing the exact same problem.

The only other thing to try is another PSU. The Seasonic one I've got is high end and I doubt that's the problem, but I've got a mini-itx system and I can plug the power cables into this board to try it.
 
I'll try a reflash just to rule it out. The thing is whether it works or not it I'm unhappy with all the problems it's given me and just want to RMA it now.

I've got the 8 pin plugs in. You definitely don't need both for running at stock clocks - that's for LN2 type overclocks.
 
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