Picking a new power supply for my computer

August 4, 2006 5:37 AM

My computer's power supply is dying. I want to get the right replacement, and install it correctly.

The power supply makes a horribly loud grindy noise when I turn it on, though if I send the computer to standby and wake it back up five or six times in a row, it stops. Don't know enough about these to tinker with it safely, so I'd rather spend fifty bucks on a newer, quieter one. (And, y'know, not melt the whole shebang down.)

Problem is, I don't know what I need to get. The kind I have (RaidMax ATX 12v, KY-450ATX, 350 watts) isn't being sold anymore. I can go for a higher wattage without breaking things, right? Would it be best to just yank the old one out of my computer and bring it to the store with me so that I know the new one will fit? If the new one has extra fans in places the case does not have vents, will that be a problem?

Is there anything more to installation than bolting the thing to the case and connecting the power cords? I've dug around inside the case long enough that I know what plugs in where. I've just never replaced one of these before.

posted by cmyk to Computers & Internet (14 answers total)

One thing you might want to try is using canned air to blow out the fan area. Sometimes they can get dusty which messes things up. I blow out the MB fan and other fans on my computer every few months or so to keep them happy.

A larger wattage fan is good, lower wattage is bad. Also check to make sure you have the right wattage power supply for your computer.
posted by JJ86 at 5:59 AM on August 4, 2006

Replacing your power supply is relatively simply. Like you said, pull it out, screw the new one in and reattach all the molex (power) connectors.

You'll be ok with a more powerful PSU but chances are you won't really need it. If you've been ok with a 350W PSU thus far theres no need to go more powerful. A more powerful PSU means a hotter and all around louder PC.

A quick google search reveals a couple links showing how easy it is to replace: LINK 1 LINK 2. If thats not enough info poke around Google a bit more searching under "building a pc" or something to that effect.

Newegg is a great place to pick up PC hardware. Just buy most any ATX PSU at 350W. You may want to look into "silent" (EXAMPLE) running PSUs if noise is an issue.

If you have any question you can email me.

Hope that helped!
posted by ASM at 6:04 AM on August 4, 2006

I'd like to make a slight edit to my post above...If i remember correctly, most the time you have to pull out a good part of the hardware in order to get the PSU out. Not a difficult task but may seem a bit daunting if you've never done it before.

Like I said, poke around google a bit, theres tons of "build you own PC" guides. It really is a piece of cake.
posted by ASM at 6:12 AM on August 4, 2006

I can go for a higher wattage without breaking things, right?

Yup. Though if you get a really high rated one it might not be great efficiency wise for the load you need.

Would it be best to just yank the old one out of my computer and bring it to the store with me so that I know the new one will fit?

It's an ATX power supply; it should be a standard size (6x3.5x5.5") with standard mounting.

If the new one has extra fans in places the case does not have vents, will that be a problem?

All ATX PSU's should have intakes for the inside of the case and an exhaust at the back where there's a big hole in the case. If you get a PSU with an intake fan at the bottom (quite common) but your case has a solid shelf the PSU rests on which will cover it, yes; that's bad.

Is there anything more to installation than bolting the thing to the case and connecting the power cords?

Not really. It can be fun routing the cables neatly, but that's about it.

I like Tagan atm; this 380W should be a safe choice, push-pull fans on the front and back, well built, quiet, and enough cable to rig a suspension bridge, plus neat velcro cable ties.
posted by Freaky at 6:28 AM on August 4, 2006

Best answer: As others have said, the only problem with your power supply is a bad fan. You can try to repair it by cleaning out dust, and possibly applying a drop of oil to the axle/bearing area. You could also try replacing the fan, though this isn't as easy as it sounds because you will probably have to splice wires or solder. Also important to note, there are electrocution hazards inside the power supply!

For a replacement, virtually any ATX power supply will work perfectly for you. Despite what you will be told, there is absolutely no need to worry about name brands or extra high power levels. Those things can't hurt, of course, but any $10-15 supply, and any watt rating >=250W, will do nicely.
posted by Chuckles at 7:00 AM on August 4, 2006

For what it's worth: I have taken apart 3 power supplies in the last few days. 2 of the three had fans that simply plugged onto the PSU bread board -- they could have been replaced easily and cheaply (80mm fans, I think, a few bucks from a computer store).

The fan is the only moving part in your power supply, so it's really the only thing that could make a grinding noise. I'd take it apart and see how hard replacing the fan would be.

There are big caps that could f*ck you up in there, yes, but it's not that hard to avoid putting yourself in the circuit.

And realize that power supplies bring out the most irrational part of many computer builders. I've actually done the math, collecting current draw info. and adding up wattages -- the average computer tough guy that knows he needs a 600W power supply that cost $150 for his desktop machine is quite full of it.
posted by teece at 7:14 AM on August 4, 2006

I have to agree with teece, on the whole; unless you've got a ton of drives, anything more than 350w is usually an overkill (I've been building machines for too long) Swapping out the PS is easy, 4 screws, and take a picture of all the molex connectors (if you're nervous / unsure) with a digital cam and just use it as a reference; Conversely, you can unscrew the ps, and you should have enough slack to pull the old one out of the way, then just match the connectors one by one; A 350-400w ps for the "normal" user shouldn't cost more than $40
posted by AllesKlar at 8:38 AM on August 4, 2006

Response by poster: Thanks, y'all! Went to the shop, got something on sale, plugged it in. Easier than I was expecting it to be.

It's not whisper-quiet, but worlds better than the old one. Doesn't sound like a jet engine with a frozen chicken stuck in it.

(Freaky, that bit of shiny you linked to is going on my xmas list.)
posted by cmyk at 9:14 AM on August 4, 2006

I just had to go through this. ATX is a type of form factor: the fan, switch, and voltage setting are all on the back and doesn't matter which company it comes from they'll all be the same size. What you'll want to know is how many connectors you have and in what configuration. Your motherboard will either have a 20 or 24 pin main power slot. The site (which I'm trying to find for you ... here) I read said that if you have a 24 pin slot you can use a 20 pin connection and it'll be be fine. Some power supplies come with a 24 connector that allows 4 pins to be split from the block, so I'd check for that. You'll want to know how many peripheral power connectors (referred to as molex) you need, whether you need SATA power and power for a floppy drive (if you have it). I settled on a Antec 380Watts which replaced the Enhanced 300Watt hunk 'o' junk I had (I'm now a happy camper).

Once you put the new power supply attach all the cords but leave the main power (which goes to the motherboard) for last.
posted by squeak at 9:21 AM on August 4, 2006

Chiming in to agree with others that wattage isn't a big deal (the main exception being if you have a really high end gaming set up with multiple power hungry video cards).

I disagree with Chuckles about the brand not mattering though--some cheap ones really are pieces of crap that are far more prone to dying. Or fail to deliver steady power, resulting in weird system stability problems. Not to mention the noise factor (noisy computers being a peeve of mine, at least when it's not summer with A/C to drown them out--YMMV).

Since a bad PSU can potentially fry your whole computer, it's totally worth it to play the percentages and go with a higher quality one.
posted by Pryde at 1:23 PM on August 4, 2006

For future lookers, I guess: I would also disagree about the brand not mattering. The wattage is important, but only to the degree that you won't be able to even find one that isn't powerful enough for most computers. Quality does matter though, big time. Like your monitor, it's a component that could last you many computers - get a good one now and you won't regret it.
posted by hoborg at 3:29 PM on August 4, 2006

Despite what you will be told, there is absolutely no need to worry about name brands

I call bullshit.

Fresh out of the box, a cheapshit power supply can run your machine... but not reliably, and you'll never figure out why.

The Antec that's the same wattage as your $15 special (which, by the way, is less than half what we pay wholesale) will run you $70 or 80, but it will be *well* worth it in the long run.

Take this from someone who's personally responsible for about 500 power supplies.
posted by baylink at 3:32 PM on August 4, 2006

(which, by the way, is less than half what we pay wholesale)

It appears that you have a vested interest in up-selling consumers.
posted by Chuckles at 5:08 PM on August 4, 2006

Of course you think that; you're the one who made the assertion on which I called bullshit. :-)

Notwithstanding which, no; I sell people good product. No-name chinese power supplies have, in point of fact, been responsible for about half the failures we've had to deal with in the last, oh, 5 years or so.
posted by baylink at 5:40 PM on August 4, 2006