PSU dead?

[Davegod]

A PC I built from spares has been running fine for years started to occasionally be glitchy on boot and now won't power on.

I opened it up, unplugged everything non-essential and observed what happens:

When the PSU is turned on the MB LED comes on to show that there is power to the board but that the board is switched off.

So far so good, but if I try turning the MB on, just for an instant is starts going but then turns off. Some LEDs flash, maybe the cpu fan gets a tiny fraction of a turn and the LED diagnostic displays "FF" (which is vague other than to indicate major failure) and then everything turns off. The PSU fans do not show any sign of movement.

If I try to turn it on again there is no response at all. I have to turn the PSU off and back on again to repeat the above. This suggests to me that some kind of fail-safe has tripped in either the MB or PSU.

I tried it with another old MB & RAM (only the same video & PSU is used) out of the case and the same thing happens.

I take it the PSU is dead? It's the only thing I don't have a spare to replace it with!

 

[Fallengod]

Id say its the mobo or PSU. Decent PSU's are on sale often for under $40AR so....pretty cheap to replace at least. Heres a Corsair 500 watter basic for $41AR. http://www.newegg.com/Product/Product.aspx?Item=N82E16817139027

Heres the 430 watter for $35AR. http://www.newegg.com/Product/Product.aspx?Item=N82E16817139026

 

[VirtualLarry]

FF is normally "end of POST", IE normal reading.

 

[Fallengod]

FF means "Fully Functional". At least on my old Asus board thats what it had in the book.

 

[MarkLuvsCS]

Odd recent problem I had in an old antec 900 was the power switch itself was causing my system to shut off after boot. You can try to see if the psu would stay on by using a paperclip in the green wire pin to a black wire. Im pretty sure its the 13th on the top row (next to locking mechanism) from left side. You could also try using the reset switch as power switch plugging it in the motherboard differently.

 

[Davegod]

Found an old Antec True PSU and everything appears to work, except no display output since it's lacking a PCI-E 6 pin plug. Ordered a molex-PCIE adapter so hopefully that'll do the trick.

If so the upside is I've upgraded the PC from an Ath64 3500+ 2gb to a core2duo E8400 with 4gb and I'll be taking the opportunity for a much-needed Ubuntu refresh.

 

[Davegod]

Bah, still won't power up with the PCI-E 6 pin adapter.

Without the 6 pin plugged in, everything definitely works except for no video output. I plug it in and we're back to the board cutting out a fraction of a second after turning it on.

A bit of googling strongly points towards the PSU being unable to deliver enough juice. But I have doubts. Although it's only a TRUE 430w, the setup is now exactly what I was running as my primary rig a few years ago without issue. Secondly, bearing in mind my earlier posts, this issue has now been identical on two setups where the only constant is the video card.

So I can only figure that either I have:
* One dead PSU and one that's somehow reduced capability after sitting in a cupboard for a few years, or
* The video card has developed a fault that only triggers some fail-safe when receiving power through the 6 pin PCI-E.

 

[dma0991]

I'm going with the possibility that both your PSUs are not reliable anymore.

 

[VirtualLarry]

Some video cards have fault LEDs. You might see if yours does. Then it might indicate not enough power, etc. Some NV cards sound an alarm if there's not enough power.