ATX boards don't self generate -5V DC. That rail was deleted from the ATX spec around years ago because only certain ISA cards used it, and ISA expansion buses had ceased to be included on modern systems - even many industrial ones.

Ok, just wanted to make sure before I went searching for some with -5v if it wasn't necessary.

And check out what is available on eBay. Every possible combination of adapter to add -5v.

24-pin input to 20-pin output (probably the only one that would really ever be needed when using a new power supply).
http://www.ebay.com/itm/E24N-5VT20Y-5V-EPS-AT … A-/252903979500

24-pin input to 24-pin output:
http://www.ebay.com/itm/ANTRON-E24N-5VT24Y-5V … A-/262957463058

20-pin input to 20-pin output:
http://www.ebay.com/itm/ANTRON-E20N-5VT20Y-5V … A-/262956124134

Trust these way better than using an old as dirt PSU and hoping it doesn't blow up.

The answer is yes but normally I will just buy power supplies that have the rail from the period despite the rot caps but adapters are nice as that allows for use of modern power supplies.

Even some motherboards without ISA slots require -5V, such as the S462 MSI K7T266 Pro2. You should look it up in the manual. But the good news is that power supplies with -5V are cheap, some used 2000'ish AOpen and FSP models retail for ca. € 15 and I have good experiences with them.

As with all vintage PSUs, definitely check for failed caps.

Ive got a heap of early 2000 towers with 400w power supplies that have the -5v rail, is 0.5amp & 2.5W enough power for a sound card?

cyclone3d wrote:

Ok, just wanted to make sure before I went searching for some with -5v if it wasn't necessary. […]
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Ok, just wanted to make sure before I went searching for some with -5v if it wasn't necessary.

And check out what is available on eBay. Every possible combination of adapter to add -5v.

24-pin input to 20-pin output (probably the only one that would really ever be needed when using a new power supply).
http://www.ebay.com/itm/E24N-5VT20Y-5V-EPS-AT … A-/252903979500

24-pin input to 24-pin output:
http://www.ebay.com/itm/ANTRON-E24N-5VT24Y-5V … A-/262957463058

20-pin input to 20-pin output:
http://www.ebay.com/itm/ANTRON-E20N-5VT20Y-5V … A-/262956124134

Trust these way better than using an old as dirt PSU and hoping it doesn't blow up.

Hello cyclone3d!

I've still got a Mercury 400W PSU, which I brought brand new from Maplin Electronics in the UK back around 2005, with the required -5v rail for my ATX board with ISA slots and sound card:

Trouble is, it's a MERCURY PSU. (SCREAM!!!)

I've done a search on eBay for other better PSUs that still use the old pre ATX 1.2 standard (where -5v first became optional, before being eliminated with the ATX 2.x standard). Unfortunately, it's 2018 so no go there. (Thus far).

So thanks for the eBay adaptor links (which are still current as of the date of this post) that'll finally enable me to use a modern ATX PSU with my old Celeron 400A ISA system, before my Mercury PSU does live up to it's bad reputation and possibly goes Darkside and kills my build.

What kind of systems are you building?

-5V can be needed for some old sound cards, but there is a bigger issue when using a modern PSU for old systems, particularly the more demanding ones: since P4 and Athlon64, CPU (and PCIe) power has been delivered from the +12V line and nothing much comes from the +3.3V and +5V lines. So recent PSUs can deliver massive currents over one or two +12V rails, but relatively little on the rest. But prior to that, CPU and AGP power came primarily from the +5V line (and +12V was only for drives). With really old stuff, that doesn't matter too much, but with ATX systems, they might be dual CPU or late era AthlonXP. In that case you want lots of power on the +5V line, particularly if you intend to use a heavy AGP GPU.

Fortunately these are two birds you can usually kill with the same stone - PSUs with -5V also tend to deliver most of their power on the +5V line, PSUs without -5V invariably do so on the +12V line. I recently acquired a Fortron Source Power 350W PSU from the early 00's for this very purpose. Weighs a ton and can deliver 30A on +5V. No plans for a build that will truly challenge it, but it's good not to have to worry about it.

Just got this surprisingly heavy (for a 350W supply) replacement for the (possibly dodgy) 10 year or so old Mercury power supply of my Celeron 400A build:

Yep. It's a Seasonic. Built like a tank.

Should be OK though, even with just 20A on the +3.3 and +5 volt rails:

However, note the lack of a certain -5V rail and associated white cable on the ATX connector for ISA slots:

Never mind, it's alive! 😀

Still, at least it'll keep, until the http://www.ebay.com/itm/E24N-5VT20Y-5V-EPS-AT … A-/252903979500 arrives.

(Well, once it makes it out of New Jersey, USA, then goes international to Jolly Old England. 😜 )

dionb wrote:

What kind of systems are you building?

-5V can be needed for some old sound cards, but there is a bigger issue when using a modern PSU for old systems, particularly the more demanding ones: since P4 and Athlon64, CPU (and PCIe) power has been delivered from the +12V line and nothing much comes from the +3.3V and +5V lines. So recent PSUs can deliver massive currents over one or two +12V rails, but relatively little on the rest. But prior to that, CPU and AGP power came primarily from the +5V line (and +12V was only for drives). With really old stuff, that doesn't matter too much, but with ATX systems, they might be dual CPU or late era AthlonXP. In that case you want lots of power on the +5V line, particularly if you intend to use a heavy AGP GPU.

Fortunately these are two birds you can usually kill with the same stone - PSUs with -5V also tend to deliver most of their power on the +5V line, PSUs without -5V invariably do so on the +12V line. I recently acquired a Fortron Source Power 350W PSU from the early 00's for this very purpose. Weighs a ton and can deliver 30A on +5V. No plans for a build that will truly challenge it, but it's good not to have to worry about it.

Hello dionb!

Phil's video below tests what happens when you do use a modern PSU with a system that relies heavily on the +5V rail (Socket A for example):

https://www.youtube.com/watch?v=efK7mw8eYiE

Hope this was of some help to you.

I love those Seasonic power supplies. They are very high quality. I just ordered 3 more of them a couple days ago.

Quite a while ago, there was a place selling the higher wattage ones for only slightly more. I should have bought more when they were still available.

Well, it's finally time to retire the old Mercury PSU and replace it with the Seasonic...

...because the http://www.ebay.com/itm/E24N-5VT20Y-5V-EPS-AT … A-/252903979500, with that -5V ISA power supply conversion module for my Yamaha Audician 32 ISA sound card, has finally arrived here in the UK from the USA! 😁

Now my Celeron 400A Mendocino build, with all the AGP, PCI and ISA things, is Seasonic powered! 😀

You can tell it's quality when you get an "Oh. Yeah!" moment, just from the feel of toggling that Seasonic's power switch. 😉

POSTing and booting up just fine! 😀

Between the Seasonic PSU, and getting a replacement system HDD (a Western Digital 60GB WD600JB, to go with my Western Digital 120GB WD1200JB data HDD), I can finally do all the Windows 98se things, without my retro build croaking on me at random! Yay! 😀

Hello dirkmirk!

dirkmirk wrote:

Ive got a heap of early 2000 towers with 400w power supplies that have the -5v rail, is 0.5amp & 2.5W enough power for a sound card?

From the previous experiences with my build, and a Yamaha Audician 32 ISA sound card, I would say yes.

Outtheredude wrote:

that -5V ISA power supply conversion module for my Yamaha Audician 32 ISA sound card, has finally arrived here in the UK from the USA! 😁

Would you be willing to test the Audician 32 with and without a -5V rail? It's not known to be a card which requires it and the associated information resources should be updated if they're inaccurate.

gdjacobs wrote:

Outtheredude wrote:

That -5V ISA power supply conversion module for my Yamaha Audician 32 ISA sound card, has finally arrived here in the UK from the USA! 😁

Would you be willing to test the Audician 32 with and without a -5V rail? It's not known to be a card which requires it and the associated information resources should be updated if they're inaccurate.

Good question. I did take the "belt and braces" approach to ensuring that my Celeron 400A Mendocino build had -5V power to the ISA bus, for a sound card that probably doesn't need it anyway. Unfortunately, I am quite busy over the next month or so, but as soon as I'm free to do so I'll have a look at that, hopefully with a forthcoming purchase of 'Duke Nukem 3D'. 😉