Overclocking New Build has stopped working - serious issue?

Hi folks,

Sorry to post a problem as my first post but this has me stumped so far. I have been building a new core i5 system around a gigabyte ud3r. Up until yesterday everything was running fine, even to the extent of some moderate overclocks. I ran several burn in tests including intel burn in and everything seemed stable. Then I ran the Prime 95 torture test intending to leave it overnight. Within seconds of the test starting the power went off and the PC refused to start. Now I am seriously worried I have killed my CPU but have no way of testing this. The PC literally does nothing when I press the power button (which gives me vague hope it is the PSU) but I really don't understand why this would all suddenly become an issue after a week of stability. Please help - this is supposed to be our Christmas present!

CPU: Core i5-750 - Bclock 200, Multiplier x18 running at 1.36v (adjusted by the mobo automatically)
Cooling: Corsair Hydro H-50 plus 4 case fans
RAM:.Skill 4GB Ripjaws PC3 12800 - 1600Mhz 7-8-7-24
Mobo: Gigabyte UD3R
Power: BeQuiet 650W
Gfx: XFX Radeon HD5770
HDD: Samsung Spinpoint F3 1TB
DVD: Sony DVD R/W


Note: I have not manually set any of the voltage settings but let the mobo manage these with the Load Line Calibration feature

Many thanks

Alex

 

I'd say you need to test the PSU

 

OK - PSU is in fact working but only for a microsecond then the PC powers off. Have checked the cooling connections and they are fine. Have also tested voltage on the P8 connector. Interestingly if I run it without the P8 it runs for a few seconds before turning off again. Does this essentially mean I have fried my processor or mobo? Any other component would give an error beep before fail right?

 

Sounds like a PSU problem to me. Do you have another one you can swap it out for, or another rig you can test this one in?

.

 

The PSU runs my old Athlon 64 system no problem so looks like the power is OK

 

Right - quick update. Have bought a new PSU as the old one clearly was causing an issue despite appearing to work. Have put in a coolermaster silent pro 700w which looks pretty hefty. Now the PC will boot again (have reset to non-overclocked settings) and will even load windows. However Windows now hangs with no error messages immediately upon entering user name and password and I am wondering if the PSU did some wider damage when it went. Took a few tries to even get the PC to boot as far as windows. Am running an UBCD cpu burn in test right now (7m iterations with no issues yet) and will run the rest of the test suite but it's still looking a little precarious

EDIT

Well it gets more and more interesting. If I connect the HDD to the motherboard SATA controller (controlled by the i5) then the system hangs and reboots constantly. However if I connect it to the Gigabyte controller on the board then it works fine. Have put the mobo up for RMA as I reckon this is pretty conclusive proof that the mobo is screwed. HDD also works fine on my old system