How big of PSU will I need?
 

OK, This is everything that is going to run off of a PSU.

Epox 8RDA+ Mobo
AMD Athlon 2400+ (Not going to OC)
2 sticks 512 MB (1 Gig total)
Western Digital 80 Gig
Liteon 52x48x52 CD-R/RW
ATI-Radeon 9700 Pro
1 120mm Case fan
[And possibly 1 small LCD screen]


That's it, no other fans (Water cooling)


Will a PSU with 250 Watts total work? It has 150 Watts on the 3.3v/5v together.

I'm planning on building a VERY small case and I want to use a 1U Rack Server PSU for this computer. Will it work?

You will need at least a 400W PSU or your will risk destroying hardware. Sorry.

Re: How big of PSU will I need?
 

I believe that motherboard draws power for the CPU from the +5V rail.

The Radeon 9700 also draws substantial power from the +5V rail.

I'd suggest getting a supply that provides at least 200 Watts for the combined 3.3/5V rails alone. (And, because newer motherboards draw CPU power from the +12V rail, if you want the supply to have any long term usefulness, it should have a substantial rating for the +12V rail as well.)

I just love sarcastic remarks...

Anyway, I've decided to make the case 1" wider and use a standard PSU. I'll be using my 350 W Enermax PSU from another case.

Thanks for the replies though... Except for Airspirit's Smart ass remark, it was helpful!

That was not a smart ass remark. His thoughts are well regarded here. He made a simple response to your inquirey.

BrianW

If your not going to OC, 250 watts should be enough, but with that video card I'd go with 300 watts just to be safe.

I've got a palomino running on a 180 watt PSU, but its got a low power video card.

I'm running a t-bred B o/ced to 2.4 ghz, an OCed geforce 3 ti200 a dvd burner, 512 mb RAM with a 120gb maxtor HD on a 300 watt PSU with no problems at all.

You can not run those parts on a PSU less than 300W. I've seen the results and it isn't pretty, and that was with a lower draw GPU. That card sucks power like a mutha, and that chip isn't going to help you either.

As for you considering that a smart ass remark: it wasn't. I was a bit taken back that someone would want to attempt to run a high end machine on a PSU that would barely support the bare motherboard and chip, but hey ... I've had a lot of experience with people trying to cut corners on power supplies and it is NEVER pretty. If they're lucky they just blow the PSU. If they're not, they have a very large and ugly paperweight. Hell, I've done it myself once.

That 350W PSU will be pushed to the limit, but as long as you do NOT overclock, it may do the job ... but don't be surprised if its life expectancy is lessened dramatically.

I have to disagree with you airspirit.

Lets take some examples from SPCR.

3.06 P4; Radeon 9800; DVD+RW,etc, under heavy load the 300W PSU started to have some coil whine.

How about the P4 2.53 at 2.85 with a Geforce4 4600, 300W PSU no problem.

Or 1.33 ghz T-bird, Radeon 9700, once again 300W PSU no problem.

I think the 8rda+ draws CPU power from the 5v, but that 250W one will probably have enough power. If the mobo uses 12v for the CPU power, the 250W should handle that without a problem; assuming its a good PSU.

Here's my thoughts:

Why would you spend hundreds of dollars on high quality computer components, and skimp on the powersupply. If you buy an over rated power supply the only thing that will happen is it will run cooler. If you buy an under rated power supply, you will have a hotter ps, you will have an unstable motherboard, and you may damage your computer system.

For me it is wuite simple, pay the extra 30 bucks and get one with 100 more watts than you need.

BrianW

OK, screw the 350, I have a 400 I'm going to pull from the case my computer is in now. My brother won't like it, because I'm giving him this case, but I don't care. He can use the 350 with his XP 1600+ and TI 4200.

Thank you guys again for helping me.

Airspirit, I apologize for calling you a smart ass. From the way you stated your reply, it sounded like you were being a smart ass. I apologize.

Yeah, Zhentar, you're talking about a P4. Phantom is talking about an AMD ... and a watt sucking AMD at that. I've set up multiple NForce2/2X00+ systems with high end graphics, and I've actually nuked a GOOD 350W PSU on one of them with only minor overclocking. That P4 isn't going to suck the juice like Phantom's AMD will, hehe.

Phantom: no problem ... you wouldn't be the first to tell me I come across as a dick. I'm just one of those very blunt people that tries to keep things plain and simple (a real "no spin" person as opposed to that no-talent hack O'Reilly ... the ass-clown).

Well airspirit, lets reference a very useful webpage here....

Processor Electrical Specifications

I'll assume he has the 1.6v 2400+ which puts his max heat dissipation at 65W.

A P4 2.4C on the other hand has a "thermal design power" of 66.2W. Whether this is even full load is questionable- The willamettes thermal design power was 75% of the max dissipation. The 3.06 I mentioned earlier is listed at 82 watts. A 3200+ barton gets 77 watts.

The toasty AMDs and cool pentiums were the old days of P3s and T-birds. If things continue as the are, the roles will be reversed soon enough.