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View Full Version : If you buy a 500w PSU, but you only use say 250w of it...



hoppipolla
January 7th, 2010, 02:43 AM
What happens to the other 250w? I ask this because I am considering spending an extra fiver and getting a 500w PSU instead of a 400w, but I don't want my pc to sap any more power unless needed (like let's say I upgrade the graphics card or whatever). So... yeah, that's my question! Does anyone know? :)

Hoppi!

pwnst*r
January 7th, 2010, 02:46 AM
Nothing happens to it. It's not like it uses 500w just because that's what it's rated. Come on, man...

xuCGC002
January 7th, 2010, 02:59 AM
Nothing happens to it. It's not like it uses 500w just because that's what it's rated. Come on, man...

This.

...Which reminds me, I need a new PSU.

Old_Grey_Wolf
January 7th, 2010, 03:07 AM
Nothing.

For an very rough analogy, I have a car that produces 250 horse power (HP). If I just drive around the countryside at a leisurely speed, I don't use all 250 HP. I may use 150 HP and get 30 Miles Per Gallon (MPG). If I pull a 2,000 pound trailer or try to go from 0 to 60 MPH in 4 seconds, I could use the full 250 HP; however, my gasoline usage could be 14 MPG while doing it.

Bartender
January 7th, 2010, 03:20 AM
There is one thing to consider - generally speaking, PSU's are most efficient when they're running at about 60 to 80% of their rated output. You can check this out by looking up some PSU tests at SPCR or Anandtech or whatever.

The 80+ standard (http://www.80plus.org/news.htm) is probably the most well-known standard right now. I think there's a Bronze, Silver and Gold rating within the 80+ program. Let's say you had two Bronze-rated PSU's. One's a 350W, and the other's a 600W. You're powering a PC that uses 150W tops. Most PC's don't even get to that unless you stuff a couple of high-end graphics cards inside.

The 350W PSU will be more efficient than the 600W PSU because it's running closer to the most efficient part of its output curve.

Our big old Xeon-powered 3GHz Dell workstation with an Nvidia EN8400GS card only pulls about 105W at idle according to a Kill-A-Watt meter. Almost all newer CPU's pull less power than the old Netburst P4's.

hoppipolla
January 7th, 2010, 03:45 AM
Nothing happens to it. It's not like it uses 500w just because that's what it's rated. Come on, man...

o.O

Well it could keep more humming than a 400w supply just because it's got power running through it... I don't know how the inside of a PSU works in detail do I?

pwnst*r
January 7th, 2010, 03:47 AM
You have the internet, look it up.

hoppipolla
January 7th, 2010, 03:54 AM
You have the internet, look it up.

I think you just like an excuse to act condescending, whether or not you actually know the answer to something ._.

Hwt
January 7th, 2010, 04:05 AM
o.O

Well it could keep more humming than a 400w supply just because it's got power running through it... I don't know how the inside of a PSU works in detail do I?

My 650W Corsair PSU, which probably has about 450 or so watts being pulled out of it, is actually pretty quiet.

By the way, I wouldn't recommend buying a new PSU unless you plan on upgrading/adding hardware, or unless the current one is just crap.

Anyways, cheers Hoppi. I hope you find the right PSU for your needs.

hoppipolla
January 7th, 2010, 04:12 AM
My 650W Corsair PSU, which probably has about 450 or so watts being pulled out of it, is actually pretty quiet.

By the way, I wouldn't recommend buying a new PSU unless you plan on upgrading/adding hardware, or unless the current one is just crap.

Anyways, cheers Hoppi. I hope you find the right PSU for your needs.

the current one is crap. lol

There's something wrong with it meaning it's MEGA noisy when the pc first boots, and I can't really be bothered to try to open it up and work out what's wrong! I use those micro-ATX small form factor PSUs so they cost a little more, but hey it's all good and my PC is nice and light/small!

Gizenshya
January 7th, 2010, 04:14 AM
I think you just like an excuse to act condescending, whether or not you actually know the answer to something ._.

It's fun. You should try it sometime.

Skripka
January 7th, 2010, 04:21 AM
the current one is crap. lol

There's something wrong with it meaning it's MEGA noisy when the pc first boots, and I can't really be bothered to try to open it up and work out what's wrong! I use those micro-ATX small form factor PSUs so they cost a little more, but hey it's all good and my PC is nice and light/small!

Why micro-ATX? You like having to use tweezers to work on your machine?

Gizenshya
January 7th, 2010, 04:23 AM
the current one is crap. lol

There's something wrong with it meaning it's MEGA noisy when the pc first boots, and I can't really be bothered to try to open it up and work out what's wrong! I use those micro-ATX small form factor PSUs so they cost a little more, but hey it's all good and my PC is nice and light/small!

... the PSU is mega noisy? Does it stop or change if you slap it (even if its for a second)? I've had that happen before, and it is usually a PSU cooling fan going out. If it isn't the fan... I don't know what it could be, but I wouldn't use it anymore :p

Ohh, and if it ever suddenly stops being noisy... it's not a good thing! Just unplug it and get a new one.

If it's the fan, just change it out and you're fine. It is probably an 80mm fan, and those are about $3 even when they are overpriced at BestBuy.

As someone else mentioned, I wouldn't buy a PSU unless you're going to upgrade.

Ohh, and blow the thing out. The only fans I've had go out are the ones that have become unbalanced because of dust buildup on the blades.

hoppipolla
January 7th, 2010, 04:26 AM
... the PSU is mega noisy? Does it stop or change if you slap it (even if its for a second)? I've had that happen before, and it is usually a PSU cooling fan going out. If it isn't the fan... I don't know what it could be, but I wouldn't use it anymore :p

Ohh, and if it ever suddenly stops being noisy... it's not a good thing! Just unplug it and get a new one.

If it's the fan, just change it out and you're fine. It is probably an 80mm fan, and those are about $3 even when they are overpriced at BestBuy.

As someone else mentioned, I wouldn't buy a PSU unless you're going to upgrade.

Ohh, and blow the thing out. The only fans I've had go out are the ones that have become unbalanced because of dust buildup on the blades.

Hmm, I'm now VERY tempted to try fixing this lil devil O.O

It probably IS just the fan... yeah alright I'll give it a blast, I mean I guess you're right I could just change the fan and it would probably be good to go!


Why micro-ATX? You like having to use tweezers to work on your machine?

haha well I used to have very large PCs for a bit, but now I like something light and small and manageable! Even the case is pretty small, it's like a normal pc tower case but scaled down so it's closer to the width of a floppy disk drive than a cd drive (and no I don't still use floppy disk drives! ^_^ )

pwnst*r
January 7th, 2010, 04:26 AM
I think you just like an excuse to act condescending, whether or not you actually know the answer to something ._.

Maybe you shouldn't be so sensitive and be more open to honest advice.

hoppipolla
January 7th, 2010, 04:29 AM
Maybe you shouldn't be so sensitive and be more open to honest advice.

well maybe you should express yourself in a more constructive and less condescending way.

00ber n00b
January 7th, 2010, 04:31 AM
Maybe you shouldn't be so sensitive and be more open to honest advice.

Maybe you should go troll around on 4chan.

JDShu
January 7th, 2010, 04:32 AM
well maybe you should express yourself in a more constructive and less condescending way.

c'mon its what he does XD nothing to get too annoyed over.

The engine analogy is a good one though, your computer just has the potential to draw more power.

pwnst*r
January 7th, 2010, 04:33 AM
Maybe you should go troll around on 4chan.

Maybe you should mind your own business. Did you even read my first post? Probably not. Go to bed.

00ber n00b
January 7th, 2010, 04:36 AM
Maybe you should mind your own business. Did you even read my first post? Probably not. Go to bed.

ooooooo! Defensive are we? Come on, man...

pwnst*r
January 7th, 2010, 04:37 AM
burr burr burr

Lol, good luck with that.

KiwiNZ
January 7th, 2010, 04:45 AM
Knock off the name calling now .Last warning

hoppipolla
January 7th, 2010, 04:49 AM
Right well anyway that brings my ebay session to an end! Fingers crossed I can get this PSU to be quiet (this lil trooper has hung on long enough to deserve a second chance! :D ) and I also grabbed a DVD-RW as my old drive is busted, a hard disk caddy and a few other random bits and pieces that I needed!

Well that worked out quite well :)

user1397
January 7th, 2010, 04:51 AM
Right well anyway that brings my ebay session to an end! Fingers crossed I can get this PSU to be quiet (this lil trooper has hung on long enough to deserve a second chance! :D ) and I also grabbed a DVD-RW as my old drive is busted, a hard disk caddy and a few other random bits and pieces that I needed!

Well that worked out quite well :)Good luck!

carbonbased
January 7th, 2010, 10:50 PM
Think in terms of "load".

Get the best quality PS you can afford. Clean, well regulated voltage is important to IC function and longevity.

Here's one site that has some tools for you to do some calculations for our PS. There are others sites too, but this is one of them: http://extreme.outervision.com/index.jsp

Exodist
January 7th, 2010, 11:41 PM
Nothing happens to it. It's not like it uses 500w just because that's what it's rated. Come on, man...
This^^
Not to mention your over all system will run cooler if the PSU isn't running hotter trying to push out the load required.

Changturkey
January 8th, 2010, 01:52 AM
What kind of case did you get? How much smaller is it compared to a normal mid tower?

SmittyJensen
January 8th, 2010, 02:05 AM
It's fun. You should try it sometime.
maybe if i was 13 i would. :popcorn:

PurposeOfReason
January 8th, 2010, 03:19 AM
Why micro-ATX? You like having to use tweezers to work on your machine?
Yup, all the parts are smaller and need special tweezer sized parts. :roll:

hoppipolla
January 9th, 2010, 03:51 AM
Yup, all the parts are smaller and need special tweezer sized parts. :roll:

how did you see inside my case? :o


What kind of case did you get? How much smaller is it compared to a normal mid tower?

This was a little hard to specify or find anything similar online so I just took some pictures!

It's a pretty light, slimline, not-very-powerful little computer, but hey it ticks all the boxes I need it to! :)

HappyFeet
January 9th, 2010, 04:01 AM
I think you just like an excuse to act condescending, whether or not you actually know the answer to something ._.

The ignore feature is wonderful. It makes browsing around here somewhat enjoyable.

But anyway, I would go with the 500w psu.