New PSU won't start PC. Help please?

[Shrapnel]

Hi all,

I'm sat here with 2 PCs in bits. My mate's old PC is based on a motherboard I can't get a model number from. Winfast or something. He WAS using a generic 400w PSU. He's just upgraded to a new GFX card and an new Corsair TX 650 to power it. I can't get the computer to turn on using the new power supply.

Can anyone help.

Further Details :

His motherboard has a 24 pin power socket and a 4 pin power socket. It a couple of years old (PCI-E , Socket 939 with DDR1).

His old 400w power supply is 20 pin and 4 pin.
His new Corsair is 24 pin and 8 pin power.

I also bought the same psu. I have tried both in his PC and neither function (using the 24 pin plug in the 24 pin socket and 4 pins of the 8 pin plug in the 4 pin socket). I have tried them in my PC and they work. His old PSU still functions.

So, what is the problem? Why won't either work with his motherboard? What can I try?

Please help !

Here is a picture of both the 24 pin connector from the new corsair and the old 20 pin. (apart from the obvious 4 extra pins) I noticed that the 20 pin plug has a white cable 3rd in from the left but the 24 pin doesn't have any cable in that area. Normal I guess?

new 24 pin.

old 20 pin.

*edited to clarify plugs and sockets.

 

[setter]

On the 24 pin connector, 4 of those pins (left side in pic) will slide off to allow them to fit an older 20 pin socket. Also the 8 pin socket should fit using just one side of the connector (some psu's may supply an adaptor that steps 8 down to 4).

 

[Shrapnel]

Thanks for the info, but I'm aware of the above. The new PSU and the motherboard are both 24 pin. I've also used the 8 pin plug into the 4 pin socket (as I have done on my motherboard).

Using the 24 pin plug and 4 pins of the 8 pin still don't help with the situation.

Anything else I can try please?

 

[bremen1874]

Stupid and obvious suggestion:

Does the new video card have power connectors and are they plugged in?

I wouldn't suggest it but it does seem to crop up more often than you'd think.

For reference the missing wire is the -5V that was removed from the ATX specs a while back. I can't exactly remember what it was used for but I've got a feeling it may have been involved with the old ISA expansion slots. Whatever the case it's unlikely to be the cause of your problems.

If you haven't already done so it might be worth removing the board from its case and testing it with the bare minimum of components. There may be a short or something similar that the new psu is detecting and the old one isn't.

 

[Blackwhite]

Are you using any UPS unit?

 

[toon_mad]

If the gfx wasnt connected properly im sure he would here a loud screeching sound.

Im not sure on that psu, but on the back is there a red switch with the voltage number? Most new ones dont, just check anyway, it could be set wrong which may fry everything!