P6T Deluxe boot-up issues

[rcw600]

I've posted this on the Asus forum with not much response so far and hope some of the clever people on here might ba able to suggest something:

My system has been running fine since I built it 9 months ago but now I am having problems. It will not switch on after power disconnection (i.e. disconnecting the PSU from the mains). Nothing happens at all - no fans, no hard disk, no beeps, nothing on the screen although the LEDs in the start and reset buttons on the mobo are lit. Finally, when the power's been on for about 5-10 minutes it will boot up normally. I don't have this problem (so far) after shutting down if the mains power stays connected, but I do usually turn off the mains switches at night. It doesn't make any difference using the on-board power button or the case switch to try and start it so I'm sure it's not a power switch issue. Once it finally boots everything works normally. I've also noticed that a faint pop comes from the speakers once it's been connected to the mains for about 5 minutes, and right after that it will boot. I haven't changed anything on the system in months and it's not currently overclocked (all BIOS options on Auto). I am thinking this must be the mother board or the power supply but I can't find any similar reports on the web so it seems to be an unusual problem. Any ideas or suggestions for tests that will eliminate one or the other? (unfortunately I don't have access to a spare PSU). Asus haven't answered my tech support request and I can't even find a support email address for Tagan.

Thanks for any advice!

Rest of system is as follows:
6GB G-Skill DDR RAM 1600Mhz
Nvidia 8800 GTX graphics
Intel i7 920 CPU
Tagan 900W PSU
BIOS version 1102
2 x WD Raptors in RAID 0; 3 x WD 320GB in RAID 5
Windows 7 RC1.

 

[dazman]

Probably something either to do with discharge in the PSU or MB capacitors, ie not having enough juice in them to pass the circuit protection checks or some other "feature" of the PSU or MB power outage protection. Have you tried turning off the socket leave it for a minute and then turn ithe socket back on or only tried it after turning the socket off for a long time. You could also try disconnecting the power cable from the PSU to the MB to isolate if it is the PSU or MB. At your risk of course!

 

[rcw600]

Probably something either to do with discharge in the PSU or MB capacitors, ie not having enough juice in them to pass the circuit protection checks or some other "feature" of the PSU or MB power outage protection. Have you tried turning off the socket leave it for a minute and then turn ithe socket back on or only tried it after turning the socket off for a long time. You could also try disconnecting the power cable from the PSU to the MB to isolate if it is the PSU or MB. At your risk of course!

Well it turned out this was an interim state before complete failure. Wouldn't boot up at all by Sunday. I figured the PSU was probably the cause and fitted a new one which fixed the problem. PSU was only two and a half years old though, seems a bit soon for failure!