Asus P5K Premium.... Power circuits dying?

[[XC] riptide]

P5K Premium
E8500
8800 GTX
5 HD's + Optical
WC with MCR220 + Apogee + '655 pump

I ran this C0 rev. E8500 at ~4.3 @ 1.58vcore. << Yes. It needed all that. You could get it to 4.0Ghx on a little over stock vcore, but things weren't crazy as you wnet towards 4.1 and after.

Anyway the P5K board has been rock solid. Has ran quads, 65nm Duals and now the E8500. Until now....

At Stock clocks, it won't boot into the OS at anything over 1.40vcore. Stock CLocks btw. It will boot fine at stock vcore or less than 1.39.
I have changed the PSU. Same issue. I have tried booting off a SATA single drive.. same issue.

The boot cycle continues just until the Microsoft rolling bar is going to be displayed and the machine restarts. Strangely I can select a memory diagnostic in the boot menu while voltage is jacked up to 1.59vcore, and it will run flawlessly. I would have imagined the inbuilt, preboot, windows memory diagnostic would pull hard on the CPU aswell?

The only time this has happened before, was with a QX6700 that had carbonised the 4 pin connector on an old Giga. DS3. It wouldn't run for long on a high vcore as the connector heated, the resistance went up and the current fell.

The connectors are all fine on the board. This pattern is not typical of CPU degradation... in fact if it was degradation I could just give it a bit more vcore and it would be fine at a given clock.

This seems different. I guess its the power circuits on the Asus board. Its been in heavy use for the past nearly 2 years. Are we in agreement? Or would there be another issue at play? This has happened fairly suddenly. Started with OS blue screens, and crashes within a few days I was back to close to stock vcore.

[DAK1640]

Your symptoms indeed point at the mobo, and 'suddenly' also suggests PWM's loosing their ability to keep current up. Perhaps it's time for a new mobo? BTW, I have same mobo and have a 120mm fan blowing on my PWM's. Thermal runnaway is the worst.

[[XC] riptide]

Your symptoms indeed point at the mobo, and 'suddenly' also suggests PWM's loosing their ability to keep current up. Perhaps it's time for a new mobo? BTW, I have same mobo and have a 120mm fan blowing on my PWM's. Thermal runnaway is the worst.

Ya. Well theres copper heatsinks as stock on these boards, and theres enough of a cyclone in terms of wind. And free hanging power connectors flap in the wind. Bugs get caught up in mini tornadoes in my case.

I think its the board, and I think its highly unlikely to be the CPU. I've ruled everything else out. Even diconnected one of the PCIE connectors fomr the 8800 GTX to bring it down to low power state (~1xx Mhz Core).