appiah4 wrote on 2021-04-29, 07:52:
Jed118 wrote on 2021-04-28, 23:52:
liqmat wrote on 2021-04-28, 16:16:
Good to know. I have not run into any issues, yet, luckily.
I also must have been lucky - I've converted and sold a bunch of ATX systems to AT (and just did my own 233MMX with a nice new ATX supply) but I have heard of this problem. I only use decent-and-up power supplies for these conversions and so far, so good.
I can't think of any AT build that would draw power a modern PSU can't supply on +5V unless it's an anemic modern 250W unit or something. The concerns above are mostly valid for Athlon systems, and it's the first time I heard of a Dual P3 system not booting due to weak +5V.
I haven't ever owned an AMD rig, but when I first began researching a few years ago intending to build a 'best possible rig I could have built in late 2000 when I made my first all-new PC', it came up quite a bit. Phil's Computer Lab mentions the lack of amps on +5v rail in a number of his videos about building gaming PCs from mid 90's to early 2000's when the switchover to mainly +12v draw happened.
From my own experiences thus far looking at most modern PSUs, you'll find that the majority have very low available current on that +5v rail ~ in the neighborhood of 15A-20A which just isn't enough when you've got a +5v-heavy motherboard, CPU, several SDRAM modules, beefy AGP graphics card, several PCI expansion cards, etc.
In the case of my Tyan dual PIII board, with two 1.4ghz Tualatin chips, 4 PC133 512mb SDRAM modules, 4-5 PCI expansion cards, etc it just wouldn't even try to boot with any of the modern PSUs I tried (including the Corsair HX1200 which has 30A on the +5v rail) but boots and runs just fine with the old Enermax Noisetaker PSU I picked up and subsequently seem to have killed trying to recap - it had 45A on the +5v rail and 36A on the +3.3v rail. Compare that to say a modern EVGA Supernova 750 G2 which has 24A on each of those rails, a Cooler Master MWE Gold 750 V2 which has 20A on each, etc.
The Corsair HX1200 I'm planning to use has 30A each on both the +5v and +3.3v rails which should be plenty for this single Tualatin rig, especially since I'm not overclocking anything.
Retro: Win2k/98SE - P3 1.13ghz, 512mb PC133 SDRAM, Quadro4 980XGL, Aureal Vortex 2
modern:i9 10980XE, 64gb DDR4, 2x Titan RTX | i9 9900KS, 32gb DDR4, RTX 2080 Ti | '19 Razer Blade Pro