Do I need a PSU with a -5v rail?

[sltech]

I have an old Socket A board (KT7-RAID), and all of the PSUs from that time had a -5v rail. But all of the new PSUs seem to comply with the ATX12V 1.3 standard which doesn't have the -5V rail. Will one of these new PSUs work properly with my board?

 

[lenjack]

you won't need -5.

 

[Zepper]

-5V hasn't been used in PCs for years. It has been deleted from the current spec for ATX PSUs. -12V is optional now and will be the next to go. Unless your sock-A mobo has one or more ISA slots AND you use an ISA card that needs -5V, then you don't need it.

.bh.

 

[sltech]

I actually do have an ISA slot on my KT7-RAID, and there's a USRobotics Courier V.everything modem in there. If I get a PSU that can deliver 0.3A on the -5V rail, would that be enough? I've tried to find specs on that modem, but can't find out how much current it needs.

 

[Zepper]

Modem cards don't use -5V (they use +5, +12 and rarely -12) it was usually video cards that use -5. Look up the pinout for the ISA slot and see which pin number(s) is -5V, then look at the corresponding contacts on the modem and see if they are present and actually connected to anything. In many cases there won't even be a pad at the -5V location(s).

.bh.

 

[sltech]

Wow, thanks for your help! I wouldn't even have known to look for a pinout... but I found it and the modem doesn't use the -5v rail!