PC suddenly shuts down then repeatedly tries to restart.

[peterb99]

I'm new here and I've read several of the threads relating to my problem.
I had need of a specific PC so built my own:

Asus H81I-plus mobo
Pentium CPU
2 x 2G memory (Corsair)
64G SSD
Alpermann & Velte (now Plura) PCIe timecode card
W7 64 bit
All built in a 1U server case.

In full working mode the following are attached:
KVM (VGA and USB)
USB to ethernet to extend USB for a Contour Pro controller
USB dongle for software
Ethernet for local network of other devices

It has performed perfectly for over 18 months. I needed a second similar PC so duplicated the build.
Initially PC wouldn't start at all. That was traced to a faulty DIMM socket on the mobo. Replaced the mobo and then had the basic problem of intermittently either not starting or stopping suddenly. When I manage to get the PC running again I often have to go through the W7 restore process at switch on.

The only item I have not replaced is the SSD. Memory, CPU, PSU and case have all been substituted. CMOS memory reset.

I replaced the CPU as it had been in and out of the faulty mobo and another mobo when diagnosing the first fault. After I replaced the CPU in the new build it appeared to work fine for a couple of days with several on/off cycles but now the fault has returned.

 

[Paul NZ]

Is the BIOS up to date? Is BIOS 2305 on it?

 

[peterb99]

Paul, I will check that at the weekend when I next get the chance to fire up the PC. Presumably BIOS code is updated to meet the requirements of new hardware and new OS so I would expect it not to be an issue (assuming it is at least as up to date as the other PC I built)

 

[peterb99]

When I said that everything was the same as the previous one I built I had overlooked the fan.
The fan i used this time was intermittently shorting either by the metal pillars or the heatsink itself.
currently i'm testing the PC with the standard Intel fan and there are no problems.