Help needed to choose a new ATX power supply for an expanded Amiga 4000

[Reflex]

Hello,
i have a quite expanded Amiga 4000, i noticed that i have a lot of troubles with the SCSI chain with unexpected hung ups and resets. The chain is properly terminated with active terminators so it's not the problem, if I unplug some devices it seems to be working better, so I'm thinking to buy a new, high quality, power supply, now I have an unbranded ATX one with 400 WATT power, quite old.

this is my configuration:

- Amiga 4000 Desktop 64MB ram in full tower
- CSPPC 200Mhz e 68060, 66MHz, 128mb RAM
- Mediator A4000D
- Picasso IV
- Delfina Lite
- Ati Radeon 9200 128MB
- Voodoo 3 16mb
- Ethernet PCI
- 2x Hard Disk SCSI UW 15k rpm
- SSD Ata on a ACARD SCSI3=>SATA adapter
- Iomega Zip100 SCSI
- Iomega JAZ 2GB
- DVD-ROM SCSI2
- Cd-Burner 6x4x16 SCSI2
- CF IDE Adapter

what power is supposed to be enough for such a configuration?
I was thinking about 500Watt but with so much devices and expansion maybe it could be underpowered.

[QuikSanz]

You have quite a lot of stuff packed in there. You may want a 650Watt job for that one.

Chris

[Whaka]

500 or 650W is not the most important.
what you really need to look for, is the max power available on 5V rail.

something have greatly changed since the amiga and the first ATX revision, it's mostly everything moved from 5V to 12V.
nowdays, psu give the maximum on 12V.

original amiga 4000 psu is something around 90W on 5V, so you need something similar.
modern atx psu usually give 100W on 5V.

and you also have to know, as your amiga suck nothing on 12V, this can seriously unbalance modern psu regulation. and affect 5V performances.
maybe you can consider adding fictive load on 12V to prevent this. usually, it's fine without this.

but you can safely look for 400/450 modern psu. only matter the 5V, you need at least 100W (20A)
less you get on 12V, better it is for 5V and your amiga

[darksun9210]

yeah, agree on the 5V rail. if you have an SSD in there, can you not ditch the 15k drives? save a bit of power/noise/heat?

I had an A4kT, and that mainboard has an "AT" type power connector.
I had a CSPPC060/CVPPC, 128meg, CV64/3D, Digital Boardcaster32, AD516, Ariadne NIC, Vlab Y/C
couple of scsi drives for audio streams
couple of UW scsi for video,
IDE4x adapter, IDE boot drive, IDE DVD, IDE Zip
Fans. so many fans.

it actually burnt out/melted the 5V "tongues" inside the AT power connector plug. i'd have to swap in a new PSU every year or so.

currently got a "Flex ATX" PSU in my A4k, but it's not running as much as you are - but they are smaller, quieter, and the amiga PSU's were pretty weedy to begin with.
its running an A3640, 16meg on mainboard, a "bigram 256", an xsurf100+rapid road, mediator A4000di, and an IDE2CF+4gig card atm, so nothing like your setup  

https://www.overtek.co.uk/collections/flex-atx-1u-psu/products/seasonic-ss-350m1u-350w-80plus-gold-silent-flex-atx-1u-power-supply-psu
looks like this has got 16amps on the 5volt line - 80watts? have a look at what the PSU you're running at the moment puts out. volts times amps = watts

12V line is still important, as is the -12Volts, otherwise the line-out level amps fed from the audio DAC's aren't happy. found this when putting a mini-itx PSU inside an A1200. another lesson in not corner cutting.