Computer doesn't post unless psu is restarted

[August Peachwater]

Pretty sure it's been like this since I built it a month or two ago, or shortly after anyway.
But unless I flip the power supply switch after turning off the computer it does a few things but no postbeep.
All the fans will start, wait about 8-10 seconds, then the video card fan goes craaazy 100% speed.
It's at full for about 7 seconds, then it goes back to normal, then it goes back on again, then off.
Then the fans are running normal but nothing happens.

Anyway, when I do turn it off and it does work, it always takes abnormally long to post, like still 8-10 seconds.

Any ideas what's up?

 

[T_T]

My initial assessment leads me to believe your PSU is failing, but list your system components and include the specs of the PSU (the sticker, if any, that shows your rail info). Let's take a look at what you're working with first, perhaps the problem is elsewhere.

 

[JackNaylorPE]

Anything on screen ? .... my son's box will occasionally post an overclocking failure...hit the restart button or enter / exit BIOS w/o changing any settings and it boots normally ....known issue on Asus forums ..... recently started BIOS upgrade, sometimes even to same BIOS version reportedly fixes it.

 

[August Peachwater]

My initial assessment leads me to believe your PSU is failing, but list your system components and include the specs of the PSU (the sticker, if any, that shows your rail info). Let's take a look at what you're working with first, perhaps the problem is elsewhere.

CPU: AMD Phenom II X4 965 [125w]
MOB: Gigabte GA-790FXTA-UD5
GPU: HIS Radeon HD 5850
RAM: Gskill DDR3 1333mhz
PSU: Corsair 850HX

Powersupply info copied from corsair's website:
* Guaranteed to sustain its full rated wattage at an ambient temperature of 50°C
* Up to 90% energy-efficiency under real-world load conditions*
* Single +12V rail design providing up to 70A
* Multi-GPU ready
* 105°C solid state capacitors
* Active Power Factor Correction (PFC) with PF value of 0.99
* Supports ATX12V 2.3 and EPS12V 2.91 standards. Backwards compatible with ATX12V 2.01
* Auto switching circuitry for universal AC input from 90-264V
* Over Current/Voltage/Power Protection, Under Voltage Protection and Short Circuit Protection provide complete component safety
* Dimensions: 150mm(W) x 86mm(H) x 180mm(L)
* MTBF: 100,000 hours
* Safety Approvals: UL, CUL, CE, CB, FCC Class B, TÜV, CCC, C-tick