500+w PS now almost mandatory?

[Tio]

This is a companion to my earlier CPU query. I am amazed at how many forum posts/reviews associated with the Athlon64 compatible MBs highly recommend 500+w PS! It seems to me when looking at power consumption of these newer processors (and peripherals) that requirements for volts/amps/watts should in fact be reduced. Am I missing something or are people confusing inferior PSs for required power output?

I've always used HQ PSs in previous builds and have never had a failure even when running as much as 4-5 fans, 5 HDs, Athlon XP 1.8, , AGP + PCIs and ABIT KT7-Raid all off a 340w Enermax. (lol, guess this proves my most recent build was ages ago. ;)

I have a new 360w Enermax laying around and was expecting to put it to use in the new build but all the power talk has me wondering. Are all the new boards power hungry or are there a lot of wolves out there? Any insight would be appreciated.

Regards!

[Sirber]

Try this calculator :)

My P4 server at work uses 90W total.

http://www.jscustompcs.com/power_supply/

[Tio]

Nice link Sirber!

My conservatively "heavy" calculation comes in at under 300w! This compares well to an article I read not too long ago on a PS oriented site. The author/tester/reviewer stated that touting big watts is more a sales ploy for manufactures than a requirement for MOST systems. He went on to make note that rarely is there a need for more than 275w-350w...seems he may not be in lala land afterall. ;-)

Looks like my Enermax is good to go! Thanks for the info!

[dragongodz]

He went on to make note that rarely is there a need for more than 275w-350w...seems he may not be in lala land afterall.
it all depends on your system. the average person its true will probably not need more than 350W. however using that calc i need 343W for my current system and doing just a small cpu upgrade will take me to 349W. upgrade video card aswell and the 350W is passed of course. plus you really want a little overhead and not be running too close to the PS's limit. i currently have a 400W PSU so that should see my right for a couple of upgrades anyway. ;)

[Joe Fenton]

You're forgetting one thing: that 400W PSU is only 400W peak load; you need to look at the sustained load the PSU can handle. If your computer needs 300W sustained, you may need a 400W PSU because the 400W is peak and only supplies 325W sustained.

[Tio]

Yup, I do see there are variances that can make a difference. I fail to take into account that many people use a single computer for all tasks...a true multi-use full-on system. I myself seperate computers by task (i.e. i-net surfing/downloading, encoding, capturing) therefore require fewer watage hungry add-ons.

The encoding sys I am preparing to build is 3000 Venice based with everyting onboard the 2 stick laden MB except for video and 3 fans. The only twist I can forsee that might cause a 360w PS not to be sufficient is my possible o/clocking but as it stands I should be well under a 285w sustained requirement. LOL...My biggest concern now is that this 40 year old house with the old screw in fuses has enough amperage to keep all the computers running.

Thanks again guys for the insight and for keeping my brain active!

[dragongodz]

You're forgetting one thing: that 400W PSU is only 400W peak load;
actually i wasnt, thats why i said you do not want to be running anywhere close to that rating and why i said i SHOULD be ok for a couple of small upgrades that dont draw much extra. :)

[Sirber]

You're forgetting one thing: that 400W PSU is only 400W peak load; you need to look at the sustained load the PSU can handle. If your computer needs 300W sustained, you may need a 400W PSU because the 400W is peak and only supplies 325W sustained.
The calculator is for "max" needed, not average. On my WS, I calculated ~290W, at run, uses 180W.

[edit]

265W with my 19" CRT screen. (UPS calculation)

[Joe Fenton]

The calculator is for "max" needed, not average. On my WS, I calculated ~290W, at run, uses 180W.

You misunderstood me and the calculator. When I say peak as regards the PSU, I mean SURGE during powerup. This is a transitory condition that only lasts a few seconds. The peak power on a PSU will only hold for a few seconds. The sustained power of the PSU is what it will provide for more than a few seconds.

With the calculator, they are not giving a peak surge power during powerup, they are giving the maximum sustained power draw given conditions like the CPU at 100% usage and the 3D video card running a modern game. The calculators is telling you the maximum your computer MIGHT draw for an extended period of time (while playing DOOM3 for example). This MUST NOT be higher than the maximum sustained power output of the PSU, and is NOT the peak power generally given as the PSU output.

Hope that explains it a little better.

[Sirber]

I knew about the calculator. Thanks for the infos about peaks :)

Solution: always having the PC online :D

[*.mp4 guy]

I have a nice 320 wat psu, my computer is rated a 316 wats full load, and my psu has never had any problems at all. Some power suplies are actually as good as they are rated to be. For instance I used to use a "360 wat" Enlight psu, but it was unstable, then I switched out my old psu with it (I had gotten this one as a case combo) and it worked much better, even though my old psu was rated lower.

[theReal]

I agree with *.mp4 guy: a 500W no name PSU is often worse than a brand name 400W PSU, regarding sustained power and stable voltage output under load.

[Joe Fenton]

Yep. No name PSUs are really bad about hyping their high surge power ratings, and VERY quiet on how low their sustained power capabilities are. What good is a supply that can handle a 500W surge, but not 300W sustained?