Archer57 wrote on 2025-06-24, 06:49:

So, RM1000 uses DC-DC converters to generate 5V and 3.3V. Which is great, this is exactly what you want. […]
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So, RM1000 uses DC-DC converters to generate 5V and 3.3V. Which is great, this is exactly what you want.

And this is what you have to look at when buying modern power supply for 5V socketA. It matters more than current ratings, because for PSU with group regulation ratio between 5V/3.3.V and 12V is what's important, not just load itself. It can be rated for 35A 5V and may shut off due to over/under voltage when you load it with just a couple of amps at 5v with zero 12V load. Or it may blow things up if over/under voltage protection does not work properly.

Modern group regulated power supplies are unsuitable for 5V socketA, no matter how high 5V current rating is!

Said RM1000 is also basically a 150W power supply for such system, since it has 150W limit on 5V+3.3V, so have to keep this in mind. It is enough, but with old high end GPU it may be pretty close. You can see how relatively small whole DC-DC converter board is and how little cooling it has in review i linked, which in this case powers whole system.

I've been using this to power my 5V socketA system for about 3 years at this point:

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That's cutting it close, but DC-DC too and works just fine. Partly because the system is pretty mid range one. Partly because ratings here are limited by heat and this DC-DC converters can handle much higher transient loads than the rating for continuous load is.

I've also measured 5V consumption on 12V socketA - it is <~3A and depends more on USB devices and storage than anything. Fun fact - due to the same issue with group regulation old PSUs, designed for 5V systems, will not work well here. The same issues with load ratio, only in this case too much 12V load. Have to keep this in mind - such systems require modern PSU.

Or in summary - picking power supply only based on 5V current rating is a good way to get a non-functional system or even damage the hardware. Have to dig a little deeper.

Both my older units are rated for socket A AMD systems and P4 systems, But I have run my Abit NF7-S 2.0 boards with a modern PSU with little issue .. IIRC it was an EVGA 850 P2 . .which is total overkill but it was what I had spare at the time, its also a DC/DC convertor design. But since it was a test bench I did not have the setup loaded with peripherals so power draw wasn't abnormal.

Whats odd here is that 600watt Unit with 57A also has -5v output .. which is also the main reason I grabbed it . .dont see ATX power supplies that have a -5v on them that works often, usually its there but gimped so doesnt help if you want to throw a AT convertor on it and use it for old AT boards.

"My" RM1000 is a newer model: https://www.corsair.com/us/en/p/psu/cp-902008 … 1YiGVKTRLG3yrZO#
On the other hand I also got this: https://silentpcreview.com/enermax-noisetaker … 14e07af1bcc81e7
It is one of the very few independently regulated PSU - 3.3 and 5 rails are on separate rails - this means that you got those 34A on the 5V rail only for the 5V - making it one of the best retro-friendly PSU!

Enough "talking", let's see a real example of a machine! I am going to start with the best price to performance socket 462 PC as it is far cheaper and easier to build.
Next to each component I will put up the price that i paid for it, new or second hand!

CPU: Athlon XP 2800 that I got for free some years ago - price 0 USD

RAM: some Kingmax that I got from decommissioned systems many years ago - price 0 USD

CPU cooler: one of the many socket 462 coolers that I got from various old systems - price 0 USD

HDD: one of the many drives from systems that were thrown out - price 0 USD

DVD: again some unit from old computers for 0 USD

CASE & FDD: also for free was this cooler master force 500 case that came with the floppy drive - price 0 USD

MOTHERBOARD: after so many free components it is time for the first one for which I payed serious money - ABIT KV7 with VIA KT600 chipset, onboard VT1616 codec equivalent to a Creative Live. Price 30 USD. It comes with the infamous VT8237 south bridge which accepts only SATA 1 hdd's.
Excellent clearance around CPU socket allows installation of big coolers. Only 3 dimm slots with a max capacity of 3gb, more than enough for any XP build. 5 fan headers - 3 for system fans, enough to put as many fans as you want!

VIDEO CARD: Leadtek geforce 6600gt. This one I bought it brand new back in 2004. After 4 years with geforce2 mx, for me it was both a revelation - all games ran on it - and a disappointment - directx 9 games have abysmal performance! For any game up to 2003 it is more than enough to run them at whatever resolution you want at max settings. Price: around 150 -200 USD from what I remember.

PSU: Again bought new back in 2011 for around 100 - 120 USD is the Corsair TX 750 power supply. It is not modular but it has plenty of molex connectors, 25A on the 5V rail and build quality is second to none!

Fully assembled build!

nd22 wrote on 2025-06-24, 07:24:

On the other hand I also got this: https://silentpcreview.com/enermax-noisetaker … 14e07af1bcc81e7
It is one of the very few independently regulated PSU - 3.3 and 5 rails are on separate rails - this means that you got those 34A on the 5V rail only for the 5V - making it one of the best retro-friendly PSU!

That's a very nice PSU for old 5V system.

However technically on any DC-DC based PSU 3.3V and 5V are separate buck converters. Which means independent regulation and everything. In fact regulation on such PSUs is often beyond excellent - voltages will commonly stay within +/-0.01-0.02v from target at all times. The main reason they often have shared limit is heat - converters are commonly on a single board with very little cooling - it is assumed that large sustained load on this does not happen in modern systems. You usually can get full rated current for both rails at the same time, but for a limited (by heat) amount of time. In fact it would be curious to see how one of modern PSUs with decent current ratings but relatively low total limit (like 100W) behaves if extra cooling (some heatsinks) is added to this converters. May be a useful mod for the purpose of running old systems without buying rather expensive totally overkill power supplies.

Total cost: around 300 USD - take into account that the GPU and PSU were bought brand new! I replaced the thermal paste on the north bridge and the 6600GT and the system is inaudible when playing some 2D games such as Age of empires 2. However in 3d games the 40mm fans on the video card and the chipset are clearly audible!
Overall a pretty good system that will provide 80% of the performance of the ultimate socket 462 PC for a much lower cost!

Got my hands on a Athlon XP-M 3000+, its the 462 version designed to replace a desktop version .. 2.2Ghz on a 266FSB with unlocked Multipliers.

Should be a fun little chip to test !

That is a nice find. I do not have any mobile Athlons, all | got are around 40 desktop CPU's.
The system I presented is not something special; it's your typical socket A machine built with good and quality parts for a cheap price. I reused parts that I already had so only the motherboard was bought second hand. If you go for used GPU and PSU you should be able to build an exact copy for 100 - 150 USD. The performance is more than adequate for any game up to and including 2003; noise is pretty low and temperatures are OK.
The one thing missing is the monitor. I use an Eizo 21.3 inch LCD - with good colors by the way - for all my retro systems because CRT's are impossible to find or crazy expensive in my country.

nd22 wrote on 2025-06-26, 05:08:

That is a nice find. I do not have any mobile Athlons, all | got are around 40 desktop CPU's.
The system I presented is not something special; it's your typical socket A machine built with good and quality parts for a cheap price. I reused parts that I already had so only the motherboard was bought second hand. If you go for used GPU and PSU you should be able to build an exact copy for 100 - 150 USD. The performance is more than adequate for any game up to and including 2003; noise is pretty low and temperatures are OK.
The one thing missing is the monitor. I use an Eizo 21.3 inch LCD - with good colors by the way - for all my retro systems because CRT's are impossible to find or crazy expensive in my country.

Heh the chip cost 5 bucks AUD or about 3.20 USD so it was an amazingly good deal !

Now I just need to find a nice KT266 board for it, I think I have one in my collection, I was thinking of throwing it in something nice, possibly a nForce 2 Ultra board.

I would use the MSI KT880 board but its suffered bloated caps while in storage so I need to recap it and I have a EPoX EP-8RDA+Pro board to recap in the queue before it.

On the subject of CRTs I have a couple that I could use but ....Jesus the flicker hurts my brain and eyes so Ill just use my fall back a Dell 2007FP which is a good 4:3 panel.

I also started to dislike CRT the moment I started to use glasses around 1 year ago - my best friend has a CTX PR960f - one of the best CRT - and when I go to him for a lanparty I use some 19 LCD that he has in the basement and not the CRT!

A major limit of CRTs is refresh rate and image quality at higher resolutions. I have 19" AOC that can do 1600x1200 at 65Hz but the maximum practical limit is 1280x960 at 85Hz. Good enough for Athlon XP or Athlon 64 but not great for a Phenom with Geforce 980.

For Windows you essentially need an LCD that does 1600x1200 natively as that it has a 4:3 aspect ratio. It also scales down to 800x600 nicely.

Alternatively, you could get an LCD that does 1280x960 natively but it will be very old and very small screen. It can display 640x480 well. Unfortunately many instead support 1280x1024.

1920x1440 will not be supported by many old games.