Have you tried on Amazon? A AT power supply will always made some sort of noise, you just have to pick a good one.

hacxx wrote:

Have you tried on Amazon? A AT power supply will always made some sort of noise, you just have to pick a good one.

AT not ATX.
One with a quiet fan.

You can change the fan to whatever you want. Most stock fans push 35-40 CFM.

I'm curious why you want 300-450 watts.
Most dual CPU AT based servers only needed about 250 watts.
I doubt many AT PSUs were even made past 300 watts.
.

Is there a brand of AT power supplies that is quieter than others ?

With the exception of ones with worn out fans or were defective, I don't remember having one that was noisy.

I would just look for a high quality unit and swap the fan out for something like a nice Noctua. They almost always use standard 80mm fans. Worst case maybe a cable extension hooked up to a fan controller if the replacement fan is to loud and or wont work with the internal psu fan header.

Why not get a nice new (or NOS) ATX power supply with a 120mm fan and then use an ATX to AT adapter?

If you need the -5v for specific old ISA cards, youused to be able to get adapters that add -5v through the adapter.

I've been using Seasonic 80+ Bronze with active PFC power supplies with my retro builds such as this 400w:

And then use an ATX to AT adapter:

There used to be a seller on eBay that sold the adapters with -5v added but I am not finding those at all anymore.

antronst on eBay doesn't have anything for sale right now. Used to sell all kinds of adapters.

Any PSU that had its fan replaced with a modern silent 80mm fan.

appiah4 wrote:

Any PSU that had its fan replaced with a modern silent 80mm fan.

Not sure I would say that.

Out of pretty much all the AT PSUs that were available back in the day, 90%+ of them were absolute trash and horribly inefficient to boot.

At the very minimum, if you get a well-made one, you will want to replace the capacitors.

And if you get a junky one, if it dies, it can take out the motherboard and/or drives and possibly other hardware when it dies.

hacxx wrote:

Have you tried on Amazon? A AT power supply will always made some sort of noise, you just have to pick a good one.

Not true. There are these 'noise killer' PSUs. Some of them are so effective that they will stop the fan when they cool enough. Although I doubt thread's author will find 300-400W one. This is clearly later ATX power rating for a PC with some GPU in it (and I'm yet to see desktop AT machine that would require such a monster PSU).

Also back in the 90s I've been servicing a fleet of around 150 desktop PCs. From time to time fan would fail and machine would continue it's operation - PSU just got a bit warmer (of course it would reduce the lifespan of the electrolytic caps) - In my life I've seen only two or three cases of PSU failing because of the fan failure. I would say replacing the fan with a modern silent one designed for high flow, ideally with some sort of variable speed circuit is the best solution.

cyclone3d wrote:

Not sure I would say that. […]
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Not sure I would say that.

Out of pretty much all the AT PSUs that were available back in the day, 90%+ of them were absolute trash and horribly inefficient to boot.

At the very minimum, if you get a well-made one, you will want to replace the capacitors.

And if you get a junky one, if it dies, it can take out the motherboard and/or drives and possibly other hardware when it dies.

I would argue. Compared to what came after them (really cheap ATX PSUs) - most of them are rather good quality and reliable. Lot of the AT cases are going through my hands right now, I usually clean them thoroughly - PSU included and I'm really fond of the quality of these power supplies. Also it's not uncommon to find AT PSUs from Seasonic or Enermax. Even the cheaper brands usually used high quality fans from Jamicon for example. I guess there were just a handful of the PSU brands and fan brands back in the 80s and early 90s and the hell broke loose in the late 90s with the advent of the ATX.

If one cares about longevity of valuable hardware, one replaces the fan with a strong one, preferably some salvaged from retired rack servers, and skips the killer "noise killer" that drastically reduces longevity.
If you do not like the sound of real computers, use earplugs or headphones.

Early ATX PSUs, especially the Pentium 4 era when 200W PSUs with just cheap junk inside were labelled as 400W and sold inside Athlon/P4 systems were a wild west of fire hazards. AT PSUs? Not so much, really. Not all of them are top notch quality but if you come across things like Channel Well, SPI, Forton etc. they are respectably well built. Even shittier brands I've come across like TASK, AEL, Chen Guang etc. are rarely the danger early cheap ATX PSUs are.

appiah4 wrote:

Early ATX PSUs, especially the Pentium 4 era when 200W PSUs with just cheap junk inside were labelled as 400W and sold inside Athlon/P4 systems were a wild west of fire hazards. AT PSUs? Not so much, really. Not all of them are top notch quality but if you come across things like Channel Well, SPI, Forton etc. they are respectably well built. Even shittier brands I've come across like TASK, AEL, Chen Guang etc. are rarely the danger early cheap ATX PSUs are.

IIRC last generic AT PSU I had was a 235W unit and had the guts from a Seventeam PSU. And the warranty seal wasn't broken beforehand.

As for ATX, it depends on how much you're up to tinkering with a gutless wonder of that time enough to make it safe. I have several units that I turned into safe 250W units from total gutless wonders.

PCBONEZ wrote:

You can change the fan to whatever you want. Most stock fans push 35-40 CFM. […]
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You can change the fan to whatever you want. Most stock fans push 35-40 CFM.

I'm curious why you want 300-450 watts.
Most dual CPU AT based servers only needed about 250 watts.
I doubt many AT PSUs were even made past 300 watts.
.

There were a few higher wattage AT PSUs used in severs.
I had a dual slot 1 server that used 2 350w AT PSU made by antec. The server had two Pentium 2's and 24 SCSI drives. 12 of the SCSI drives were hot swapable with 2 40mm fans in the caddies. It also had 2 92mm and 1 80mm case fan, a 50mm fan on etch CPU, a ISA video card, 2 PCI NIC's, a floppy drive and 2 CD drives. Sadly when I got the server it was hardly working and the drives were removed. 😢

ODwilly wrote:

I would just look for a high quality unit and swap the fan out for something like a nice Noctua. They almost always use standard 80mm fans.

Wile I would not recommend a Noctua fan as they are rather costly and would not preform to well in a PSU I do second replacing the fan if one wants a better running and more quite AT PSU.

"What is a quiet AT power supply ?"

Any newly bought 400w ATX PSU, that is known to be quiet in operation (example: Thermaltake), fitted with an ATX->AT adapter?

A 400W ATX PSU that operates at around 150 Watts only averagely shouldn't become too loud even after prolonged operation.
Mind the minus five volts, if needed.

I am using a 600W power supply in a machine that draws 600W at start, but then idles down to around 300W. This makes the PSU operate very quietly.

As well as with regards to longevity when it comes to PSUs, for the noise do the same: Aim high, run low.

Nearly my entire fleet of pre-ATX computers runs from Delta supplies. Some I tracked down, others were OEM -- like my Dell 386 and the two Enlight cases I have. I like Delta because they're reliable, well-built, and simple. They're easy to work on, straight-forward designs that just do their job. I re-cap and replace the fan on every one of them before putting them into service.

I've tried a couple, including Panaflo, and the fan I ended up with was a Qualtek part that I can get easily (and inexpensively) from Digikey. The one I use is whisper quiet, and seems to be adequate so far based on the air temp coming from the supplies.

Keep in mind that the AT/ATX thermal design philosophy relies on the PSU fan not only to cool the supply, but to draw cool air from outside and exhaust warm air from inside the case. My former Pentium II build, with a baby AT motherboard in a mini tower case, was so packed full of stuff (SCSI, LAN, MPEG2, Voodoo 5, Zip drive...) that I used the front bezel's fan mount to add a second low-noise fan just to help pump air through the case. Still the noisiest thing in that case was the Voodoo 5's fans.

I would also agree that 350-400W is too much for an AT build, unless you've got something particularly unique going on. PSU design is a trade-off, and they often run most efficiently when loaded ~75%. Using ridiculously high-power PSUs is not only senseless overkill, it's not running optimally either, which may have a negative impact on efficiency, ripple, and its ability to protect itself under abnormal conditions.

Like audio amplifiers, more is not better. Right-size.

dann86 wrote:

PCBONEZ wrote:

You can change the fan to whatever you want. Most stock fans push 35-40 CFM. […]
Show full quote

You can change the fan to whatever you want. Most stock fans push 35-40 CFM.

I'm curious why you want 300-450 watts.
Most dual CPU AT based servers only needed about 250 watts.
I doubt many AT PSUs were even made past 300 watts.
.

There were a few higher wattage AT PSUs used in severs.
I had a dual slot 1 server that used 2 350w AT PSU made by antec. The server had two Pentium 2's and 24 SCSI drives.

I'm aware of that which is why I said "most".
Any time you use lots of drives you need lots more power. It adds up fast.

dann86 wrote:

ODwilly wrote:

I would just look for a high quality unit and swap the fan out for something like a nice Noctua. They almost always use standard 80mm fans.

Wile I would not recommend a Noctua fan as they are rather costly and would not preform to well in a PSU I do second replacing the fan if one wants a better running and more quite AT PSU.

I agree. I don't like Noctua either.
If you really dig into their specs and performance reviews their advertising is mostly hype.
The real reason they are quiet is because they don't move much air for their diameter.

If the goal is quieter you are better off using a thicker or a larger diameter (than original) fan so you can move the same amount of air at a lower RPM.
That's why so many PSUs went to 120mm over the old 80mm fans.
.

SirNickity wrote:

Nearly my entire fleet of pre-ATX computers runs from Delta supplies. Some I tracked down, others were OEM -- like my Dell 386 and the two Enlight cases I have. I like Delta because they're reliable, well-built, and simple. They're easy to work on, straight-forward designs that just do their job. I re-cap and replace the fan on every one of them before putting them into service.

Totally agree. Delta makes kick-ass PSUs.
There are TONS of them available cheap as OEM units from old Dells and HPs.
People miss them because they get advertised by the HP or Dell model number instead of by the PSU model number.
Just have to watch out for those with proprietary pinouts.
If the proprietary is a problem then (most of them) you can replace the wire harness with a standard one from a dead PSU.

I scored two 10pc factory cases of never used NOS 250w AT PSUs at a local auction few years ago.
I usually rebuild over using a new one so I've only used 2 or 3 of my NOS reserve.
.

retardware wrote:

If one cares about longevity of valuable hardware, one replaces the fan with a strong one, preferably some salvaged from retired rack servers, and skips the killer "noise killer" that drastically reduces longevity.
(...)

Yeah... my 3 20+ years old PCs with 'noise killer' AT PSUs had a good laugh reading this 😉