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First post, by fitzpatr

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Hi everyone,

I've decided to send a request to Seasonic for them to produce a Retro-Friendly PSU. I know that it is unlikely to actually work, but why not try? (I love exercising my futility muscles, maybe?)

I am asking Seasonic because of my excellent experiences with the brand, and the excellent reputation it has among computer enthusiasts. It would certainly be a great gesture of good will towards a community of very dedicated computer enthusiasts.

Here are the specifications that I have come up with:

ATX 12V 1.3; At Least 30A on the 5V rail without a requirement for load on the 12V Rail; -5V Rail […]
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ATX 12V 1.3;
At Least 30A on the 5V rail without a requirement for load on the 12V Rail;
-5V Rail

Fully Modular;
ATX 20+4 Pin connector;
AT Connector (2x Molex 90331 connectors); (Either ATX or AT, user’s choice)
Connector for external toggle power switch;
At Least 6x MOLEX Power Connectors (AMP MATE-N-LOK 1-480424-0);
At Least 2x Floppy Power Connectors (Berg Connectors);
At Least 2x SATA Power Connectors

I would appreciate any feedback on the specifications or banter about this idea.

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Reply 1 of 12, by x0zm_

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I often thought about approaching some of the smaller manufacturers, especially the ones that work on small industrial or are happy with low MOQ to see what it would cost to have a fairly small run of retro friendly ATX PSUs made, get a kickstarter going so anyone interested could get one in that manufacturing run. Never actually got around to it though.

I agree it's a long shot since it is a very niche community when you compare who PSUs normally sell to, but it would be amazing to have a fully retro capable (+5v/+3.3v/-5v) PSU with all the modern comforts of modular cables and high efficiency/low noise. 😁

Reply 2 of 12, by Jade Falcon

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Not going to happen with a company like seasonic uless you back up your suggestion with money.
A cheap desktop motherboard costs about 50-75k to develop. Wile a psu is no motherboard hardware development cost big money.

That being said, try asking a few smaller companies that been around so long that they made such psu in the past.

I know thermaltake had a psu just like you posted back in like 2008 and rosewill has one that still for sale on newegg.
Your be better off getting a smaller company to bring back a older psu then for a company to make a new psu for old systems. Also up 30amp to 40 amp as some if use like dual cpu setups. 😎

Edit.
I was not trying to rain on you idea. Id love to see such a psu myself. So much so that if i was any smarter id make one.

Reply 3 of 12, by KT7AGuy

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Jade Falcon wrote:

rosewill has one that still for sale on newegg.

Which one do you like?

The RV350 and RP600V2-S-SL have been discontinued for awhile now. Having a spare PSU would be nice.

Reply 4 of 12, by keropi

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great idea about a good retro-psu - it's the key for a long-lived system!

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Reply 5 of 12, by appiah4

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Try Forton/FSP Group they used to make quality AT and ATX PSUs in the 90s and 2000s they could just reproduce some in limited runs presumably even as kickstarter projects as side money. They still build cheap versions of theşr mid ranfe studfff for OEMs in bulk. They should be approachable.

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Reply 6 of 12, by fitzpatr

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Great suggestions so far, everyone.

I am certainly open to other OEMs.

Power Draw

Perhaps there is a need for 2 PSUs. A moderate Wattage one for most use cases, and a high Wattage one for the upper end of use cases. I don't want to get ahead of myself, though.

The AMD Athlon XP 3200+ Barton is the most power hungry CPU possible to go into a 5V CPU supply board.

79.2W @ 5V is 15.84A

So 16A single CPU, and 32A dual CPU is the maximum requirement.

GPU power draw is fairly difficult to find. I expect that the GeForce FX5950 Ultra, GeForce4 Ti4600, or Radeon 9800XT would be the heaviest load on the 5V rail, but I do not know.

Cabling

For cabling, I believe that with the modular design, the same output connectors could feed either AT or ATX connectors.

I know that there are some AT boards with a third power connector. Does anyone have any details on that?

MT-32 Old, CM-32L, CM-500, SC-55mkII, SC-88Pro, SC-D70, FB-01, MU2000EX
K6-III+/450/GA-5AX/G400 Max/Voodoo2 SLI/CT1750/MPU-401AT/Audigy 2ZS
486 Build

Reply 7 of 12, by cyclone3d

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I don't really see the need for a special retro power supply.

You can get good power supplies for not that much and then just use an ATX 24-pin to 20-pin or AT with -5v added via the adapter.

The adapters also have support for the AT style switches and even come with a switch.

The adapters only cost around $16 a piece max.

Much cheaper to just adapt current, good power supplies then have a super low volume run of specialty power supplies.

Anybody want to hazard a guess at what they would have to sell each retro power supply at to break even?

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Reply 8 of 12, by deleted_Rc

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cyclone3d wrote:
I don't really see the need for a special retro power supply. […]
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I don't really see the need for a special retro power supply.

You can get good power supplies for not that much and then just use an ATX 24-pin to 20-pin or AT with -5v added via the adapter.

The adapters also have support for the AT style switches and even come with a switch.

The adapters only cost around $16 a piece max.

Much cheaper to just adapt current, good power supplies then have a super low volume run of specialty power supplies.

Anybody want to hazard a guess at what they would have to sell each retro power supply at to break even?

The best and most likely only/cheapest option is to use old designs from a company like FSP and adapt it to modern standards and utility. I would be up for it depending on the costs ofcourse, like most of us here I presume.

ATX 12V 1.3; At Least 30A on the 5V rail without a requirement for load on the 12V Rail; -5V Rail […]
Show full quote

ATX 12V 1.3;
At Least 30A on the 5V rail without a requirement for load on the 12V Rail;
-5V Rail

Fully Modular;
ATX 20+4 Pin connector + 6 pin auxiliary power cable
AT Connector (2x Molex 90331 connectors); (Either ATX or AT, user’s choice) + Connector for external toggle power switch (put this together in 1 cable and seperate later, more practical)
3 x 3 MOLEX Power Connectors (AMP MATE-N-LOK 1-480424-0);
1 x 1 Molex + floppy connector
2 x 1 Floppy Power Connectors (Berg Connectors);
2 x 2 SATA Power Connectors
1 x 4+4 pin +12 volt power cable
1 x 6 pin PCI Express power cable

make that 40A on the 5V rail for OC (my athlon is hungry, after calcs with full OC I hit 34A and my PSU is rated for MAX 36A)
6x molex? try 10.... I already use 5 on my athlon just to power the basics not counting additional fans etc.
to make fully compatible with about everything you additional support for P4 an athlons

Reply 9 of 12, by dexvx

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I think even on some Athlon 64/FX's, a strong 5V is required. I picked up an Asus SK8N/FX-53 combo and it would not boot with newer Corsair CX430/CX750 (!) PSU's with 20A 5V. Boots up fine with a 420W Antec Earthwatts or 365W Enermax Whisper.

However, I think the writing is on the wall regarding PSU's targeted for older platforms. There simply isn't much a market for them.

Reply 11 of 12, by gdjacobs

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I don't currently have data on capacitor selection or any internal shots, but the AT model they currently produce is okay (except for Teapo caps which are a 'B' grade component). If the ATX model is like that, it will be a credible option.

All hail the Great Capacitor Brand Finder

Reply 12 of 12, by Ozzuneoj

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While a good name brand unit like a Seasonic would be infinitely better in the long run, I found a cheap ATX PSU that claims to have a 40A +5v rail. Someone put it in a horribly cobbled together computer which they SOLD to a friend of mine (X2 5000+ with no thermal paste, mismatched RAM, bad caps, HDD with 0% health in SMART, whistling PSU with bad caps, floppy drive that wasn't even connected...). I was surprised to see the high +5v rail. The unit doesn't trip my PSU tester, but I could tell from the faint whistle that it had some issues. Upon opening, it has some bad caps. Only a few though... not hard to replace if I really wanted to.

If you guys are feeling adventurous, when I search for this model of PSU I find lots of them under different brand names all over the internet, all with a 40A +5v rail. Mine is an "L&C LC B400 ATX". I found these:

https://www.ebay.com/sch/i.html?_odkw=lc+b400 … 400atx&_sacat=0

There's also a discussion about replacing caps in them (and whether its worth it or not):
https://www.badcaps.net/forum/showthread.php?t=926

Now for some blitting from the back buffer.