Korean Job Discussion Forums

[Easter Clark]

Can someone please explain why a higher PSU (900w) is better than a lower one (450w)? The best I can figure, is a motherboard requires power to run things like your HDD, USB ports, blue neon light, etc. So why is "more" "better"?

[eamo]

Simply put, your PSU should match your system. A 900w PSU in an entry-level machine is a waste of money. There has been a real fad for the last couple of years for ever bigger and more powerful PSU's. But I think informed users are now realizing they are white elephants.

The big power suckers in any system are the CPU and GPU. Especially GPU. As are multiple HDD's. Lot's of RAM DIMM's will also add a fair bit to the juice requirements.

USB ports, fans, and neon lights use an extremely small amount of juice. Not worth counting really.

A typical P35/E8400/HD4850/4GB RAM/1x500GB HDD will run happily on a 450w PSU.

Add a second HD4850 for crossfire, and maybe OC the CPU, and you'll be wiser going to around 600w.

There are calculations to make to try to ensure your PSU is running at best efficiency for most of the time. Here's a good article.
http://www.anandtech.com/casecoolingpsus/showdoc.aspx?i=3413

[chevro1et]

Its also not just about watts. Having adequate amps on the 12v line(s) is just as, if not more important than having a high-watt psu. If the psu does not have enough amps on the 12v line(s) instability occurs, and then you can get into some serious problems, such as random lockups/ reboots, psu failure, and possibly damaging other components of the rig as well.

[ttompatz]

as a side note here:

Oversizing your power supply ADDS heat to the system (to it's detriment).

Fact of life:
I run a p35-DS3R mainboard with a quad core going full out, GT8600 GPU,
4 gigs of RAM, 2 ODDs and (currently) 5HDDs, 2 case fans and the stock GPU and CPU fans: it all runs fine on a stock 450 watt power supply.

It runs 24/7 and has done so for just about a year (with minor downtime for hardware changes and cleaning).

I have had NO problems with it being underpowered.

450 watts gives you just about 37 amps at 12 volts....
As chevrolet said, make sure (read the PS label) that there are adequate amps on the 12 volt lines to do what you want. (most are more than fine).

how much power do you think those HDDs really take?

Read the labels and you see that your HDDs run on 0.7 amps each.
Same with your ODDs.

Add up the amps from your labels / spec sheets. If it is under 30 amps, go with a 450. If it is OVER 30 amps, go with a 600.

There is NO NEED for any desktop PC to use a 900 watt power supply.

.

[Demophobe]

[ttompatz]

[Demophobe]

[ttompatz]

[OneWayTraffic]

Again it all depends on your system. As a rule of thumb, 450W will almost certainly be enough for anyone who needs to ask. If you're putting together a high end system that needs more it's unlikely you'll be asking here.

And the quality of the power delivered is at least as important as the amount. Many cheap '450W' PSUs can't actually deliver that much properly.

Getting a quality brand can be just as important as the size, if not more. Either ask for the 'best Korean brand', or if you really want quality go American.

Don't stinge on a PSU, it's the basis of any system.

[ttompatz]

[Sody]

Also remember that you will need a power supply that actually has the cables to connect some of the new modern video cards. I have a Geforce 9800 gx2 and even an older 500W power supply might not be compatible, especially if you run SLI or crossfire.

[Demophobe]

[ttompatz]