ATX power supply, What size?

[mechy]

Don't go by watts alone, this does not tell much. you need to look at the break down of the power rails.you can usually find the website of the mfg and check there.Specifically +5v,which is where you want as many amps as you can get.You also need to look if this rail is shared with others,this will cut down on the rating. A power supply with "seperate" rails for each voltage(at least +5 and +12) would be better.stay away from the cheaper chinese psu's,most are junk, i think i have been thru most of them and they make it a year or so on the good side,some have filtering so bad they can cause crashes and other odd behavior. I would suggest you check out some of antec's offerings. they seem to make a reasonable psu(although they do have a bottom end line too).  There is no such thing as too many watts though,and basically you can put the biggest rated psu you can afford in it.The A4000 will only take what it needs.  

Mech

[mechy]

That is a misguided advice. PSU energy efficiency is much worse with small loads. See http://en.wikipedia.org/wiki/Power_supply_unit_(computer)#Energy_efficiency

Technically yes but its a bit hard for him or anyone to calculate the exact load(especially breaking it down to what rail draws what)- checking total watts doesn't tell much. Also not all power supplies are inefficient at what you call small loads(how do you know what his exact load is? he doesn't say.). i have a similar setup as he does with csppc and mediator and i can tell you it really taxes the +5 rail.
I seriously doubt most users will take the time to check exact amp draw on +5,+12,-12 etc. I also doubt he is worried about overall power factor and efficiency.If he was he wouldn't be running a old A4000 right?
Feel free to advise him but i suspect you don't have a much better guess than i do with the information provided.

Mech

[mechy]

well the power supply that I have now is 240 watt...
moreover I made a fast simulation on a internet site that provided some kind of evaluation and it told me that my configuration has an estimated consumption of 435 Watt

So I think that I'll go for 600 Watt, taking a cheap power supply for now.

Well i have to agree with piru this time(did i say that??)that 600w is probably way overkill, for example,i picked up a high quality 380 watt for my 4000 mediator setup which is completely loaded with cards.. spend the money on quality. again wattage doesn't tell the whole story.

mech

[mechy]

it's quite the same than mine.
But what about Zorro3 and PCI Card?
CSPPC?

I think that the PPC, being a dual CPU board, is very power hungry

Zorro3 and pci aren't a problem. For many years i ran a 4000 with stock  150w psu with csppc and full of zorro cards(picasso IV,Fastlane  Z3,ethernet card,Vlab and a few hd's and a extra fan or 2 inside,and it  never missed a beat and ran 24/7.

The 604e ppc is trivial compared to say a G5 cpu and the 060 being 3.3v is not a power pig(usually less than most 040's if memory serves)... Its just not that bad power wise. you have to realize most of the large psu's are coming out for machines running the graphics cards with Uber powerfull or multiple GPU's or servers with many drives. The amiga is a trivial load compared to this stuff...I just don't see the need for more than a 400W psu in the worst case.

this is my last reply,hard to believe this has gone on this long. This isn't rocket science
I dont know what you are using to "simulate" your power requirements,but it sounds way off.

Mech

[mechy]

I'm interested in reading this thread further. I hope i will learn something useful to solve my own problem with my A4000. This one has 3 zorro boards (including Cyb64 3D, Deneb and A2386) and 3 ISA boards to use with the A2386, only one 3,5' HD, 2 floppy, and an USB internal bay, plus an indivision. Problem is the A2386 is sometimes working sometimes not, though always detected by sysinfo or sysspeed. It works perfectly when the configuration is more basic with less cards. I use a 200W ATX PSU modified by Cosmos to be A4000 friendly. I also have a genuine A4000 PSU: if i use it, the A2386 never boots properly.
It looks to me as a power problem (+5V or +12V, who knows?).
So i am puzzled when i read Piru is using 6 HD, etc with a small PSU.
I am definitly interested by a powerful A4000 PSU ready to be installed in the case.
Mechy, i'm counting on you, make us an A4000 APower :-)

HAHA i think my power supply fun is over its too much work.
seriously though dont be puzzled by the psu delima.. thats why i said the overall watts rating does not mean much. look at the break down of the psu power rails for +5,+12 etc etc.. for example,the power supply i use is rated 20 amps on +5. sounds great,BUT in real life you will not get to use all 20 amps. In some PSU's the rail is shared with other voltages like +3.3 . so if you had 3.3v stuff in use you would only get a percentage of that +5v rails 20 amps.the amiga of course in most cases doesn't use the 3.3v(except some mediator radeon hacks) and this is not a issue. but you will find some big psu's have poor +5 ratings,this is why you cant go by big wattage ratings alone. theres many other factors. cheap psu's with bad filtering can cause crashes and havoc.some chinese supplies i've seen have horrible,dirty power output.

a side note,alot of friends recommend ANTEC,and i just picked up a new 380W ANTEC EARTHWATTS that came in(rated 20A on +5) and guess what,its crap. +5 is reading 4.83v on the +5 rail with it hooked up and the 4000 on,its just low enough where the machine won't boot reliably. ahem..time to go buy another. its been my experience amigas aren't happy with much less than 4.92V on the +5.
so i say go by the amps on +5 and +12,and hope you bought a decent brand..

hope all my long winded typing helps someone out there

mech