Power Supplys

[mol3000]

2 questions about power supplys

1. How do you know how many devices you can hook up to a certain power supply??? EX: if you have 300w ps and you have 2 hd and 2 cd roms in it how do i know when to much is to much like if i want to add 2 fans to the casing???

2. If you have a power supply that you about to hook like 4 casing fans to it and other stuff do i flip that 115v switch higher or what is that 115v switch really repersenting????

[redwudz]

Somebody around here had a link to a chart or page that tells you what devices draw. On the average, you can get away with a 300W PS. 350-400W is better. This is a good quality PS, not the one that usually comes with the computer case.

I run 8 drives, CD, DVD, HD, Zip on a 350W supply and 4 case fans with no problems, but I am upgrading to a 480W, just to be on the safe side.

The selector on the power supply is to switch from 115VAC to 220AC. 220AC is more prevalent in Europe. In the US, it's mostly for large appliances. Don't switch it if you are not hooked to 220VAC.

[Faustus]

Yeah if you touch that switch it go boom.

redwudz has it correct. 9 times out of 10 you can get away with a 300w easy, though personally I'm shocked wouldn't push it as far has he has.

Also remember if you have a high end video card its sucking juice also.

I think my standard PSU these days is an Antec 350, its an all around good PSU

[rallynavvie]

You can also find the manufacturer rated power usage on their website for things like fans, hard drives, optical drives, and the like. You add them all up and make sure it doesn't come within 80% of the peak power for the PSU. If you run a lot of fans and PCI cards off your motherboard I also recommend making sure your PSU puts off enough amps on the 3.3v and 5v rails. 12v power is usually used by your processors, hard drives, and optical drives. I think video cards with auxiliary power connectors are also drawing 12v power. The more amps your PSU puts out makes for a better PSU generally.

[SquirrelDip]

Also remember if you have a high end video card its sucking juice also.

I'll 2nd that comment! I'm running an ATI 9800 Pro and was getting artifacts and eventual locking up. Problem ended up being a crappy PSU - replaced the existing with an Antec 330 and no problems.

I'm going to upgrade to 400+ as I'm needing to add a couple of internal drives.

[zzyzzx]

Check Tom's Hardware for articles on the sorry state of power supplies, and it will have you buying a better brand name next time. One crude measurement to use is the weight, as there is rampant overstating of the specs on some brands.

[gastorgrab]

How about a power supply calculator?

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