Where is the -5v rail on a Silverstone ST75ZF?

[computer]

I recently got in a Silverstone ST75ZF for a customer and unfortunately I'm just now checking it out. The -5v rail failed on both of my PSU testers. I looked at their site and they list nothing for -5v in the specs, http://www.silverstonetek.com/products-75zf.htm , and there is no -5v on the spec panel on the side of the PSU.

WTF??

I looked at Jonny's review here and I see no mention of the missing -5v.
http://www.jonnyguru.com/PSU/ST75ZF/

 

[rise]

what do you need a -5v rail for?

 

[computer]

Originally posted by: rise
what do you need a -5v rail for?

Well I have no idea. What are they for? That's kind of also what I'm asking. Why do my other 24-pin PSU's have it, and why is it failing the test on my PS tester because it has no -5v yet the tester tests for it?

 

[jackschmittusa]

-5v is not used on modern mbs.

 

[computer]

Originally posted by: jackschmittusa
-5v is not used on modern mbs.

Ok thank you. I'm curious then as to why it's on the 24-pin ATX PSU tester. No 24-pin mobo's use it?

 

[Sniper82]

is it possible its both 20pin and 24pin tester?

 

[computer]

Originally posted by: Sniper82
is it possible its both 20pin and 24pin tester?

Yes it tests both. But I would think that when a 24-pin PS is hooked up, it would know that it's not supposed to have a -5v. ? But that's not it because my other 24-pin PSU's have it, so why do my other 24-pin PSU's have the -5v?

 

[orangat]

Its probably just a legacy feature if the 24pin psu has it. Its no longer used any more on current mbs.

 

[Aluvus]

Originally posted by: computer

Originally posted by: rise
what do you need a -5v rail for?

Well I have no idea. What are they for? That's kind of also what I'm asking. Why do my other 24-pin PSU's have it, and why is it failing the test on my PS tester because it has no -5v yet the tester tests for it?

IIRC they were used primarily for ISA cards. Some power supplies still have them for compatibility; I believe the requirement was finally dropped from the ATX spec.

 

[computer]

Thanks guys for the replies.