Hi, I am thinking of getting a new PSU because mine is very outdated. The one i have at the moment is a 250 W and i do Overclock so i am going to upgrade to a 450 W what major diffrences would that make???

If you are expecting some startling performance boost then don't waste your money. Buy a quality namebrand unit. In general terms the heavier the unit the better quality. Look for something with at least 18amps on 12V rail or perhaps a unit with twin 12V rails each with say 12-15amps.

I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.

OK i dont know mush about psu's but hows this..

Output 450W -3.3V
+5V 40A
Combined PWR 220W
+12V 17A
-5V 1A
-12V 1A
+5V sb 2A

That one dosent really look any good. Only one +12V line and the +5V line is 40A which probably means they are doing a dodgy to make it look like a 450W PSU (Learnt that from jam, heh) But what is the brand anyways?

Here is a few things you should look at FIRST before the wattage.
1. Reliable Brand?
2. Does it have dual 12V?
3. how many amps on the 12V (look for 18A for single 12V and at least 15A each for dual 12V)
4. Is it 20, 24 or 20+4 pin

You also may want to factor in the cooling systems but that doesnt affect the power output. Good brands are Ernermax, FSP Group (Fortron), Antec, Thermaltake, Coolmax and Cooler Master..
I think you would be safe with them. I have a Cooler Master PSU and its been good for me, it is a much better unit compaired to my old 'Ritmo' PSU and I will probably buy more of theese Cooler Master ones when the need arises. If you follow all this you should get a reasonable PSU.

Mattwizz3 : )

Sempron 2600+ @ 2.2GHz
1Gb DDR400
Asus A7N8X-E Deluxe
200GB SATA
2X 80Gb IDE
256Mb MSI 6800 Ultra

There are some 250W PSUs out there that are much better than some counterpart 400W junk.

A PSU fortunately is one of the few components in a PC that accomodates future upgrade plans quite nicely, provided you've bought an adequate one to begin with.

The way I see it, you either will be upgrading your system very soon or in the not too distant future and the 250W PSU is bound to replaced at that point anyway.

If you had posted your current PSU's details, it would have been a much easier task making a call right now, since it's possible that you are perfectly good getting by with that 250W till your next complete upgrade or you've had a very vulnerable & hazardous PSU all along and have only been lucky things haven't gone KABOOM!

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"450 W what major diffrences would that make???"

I agree with Sabertooth. It's not going to make any difference in performance. A more powerful power supply might be needed if you add any devices to the PC.

Do yourself a favor BACKUP!

Well here is the link to the one i wanna get...

http://www.itwarehouse.com.au/warehouse/detail.htm?ProductID=CS%2DPS%2DVT450

Here are my specs too...

Cpu...

Name: Amd Athlon Xp
Code Name: Thoroughbred
Package: Socket A (462)
Technology:0.13um
Voltage: 1.616

Specification: Amd Athlon Xp 1800+ (2000)
Core Speed:1723.5 Mhz
Multiplier: x11.5
Bus Speed 149 Mhz (If I get Voltages Up It will be 170 Prob)
Rated Fsb:299.7 Mhz
L2 Data:256 Kb

Mobo: Gigabyte Ga-7vkml

Memory: DDR 768 Mb
Frequeny: 150 Mhz
512 Mb Stick: Pc2700 (166 Mhz)
256 Mb Stick: Pc2700 (166 Mhz)

Now thats all my specs right there.

Well i have researsh a bit and i have came up with a few PSU's

1. http://www.agcomputers.com.au/index.php?dir=0_67&pid=1091

2. http://www.itwarehouse.com.au/warehouse/detail.htm?ProductID=CS%2DPS%2DVTECH%2DEAGLE350

Budget Is limited...

Here's a good deal, or at least it is at the time I am posting it, a Thermaltake 430-Watt PSU for $39.99/$27.99 after rebate, free shipping, and from a reliable seller. Note that the 12-volt rail is rated 18 amps.
Ed

http://www.newegg.com/Product/Product.asp?Item=N82E16817153023

Sorry i cant buy that... I live in australia...

mmm, if you could save a little more and get this one instead it would serve you better. Its $69.

http://www.itwarehouse.com.au/warehouse/detail.htm?ProductID=CS%2DPS%2DSF%2D350P12%2D2

I understand a bit what situation you are in, I was pretty broke when I got my Cooler Master PSU. I live in Melbourne and all the local (And not so local) shops stock plenty of everything except for a good PSU, the shop I usualy go to only had really cheap dodgy ones. I found another shop and the Cooler Master seemed the best compared to the rest of the other choices. To me that super flower seems the best choice, they are a reliable brand.

Mattwizz3 : )

Sempron 2600+ @ 2.2GHz
1Gb DDR400
Asus A7N8X-E Deluxe
200GB SATA / 80Gb IDE
256Mb MSI 6800 Ultra

gmanychl this info may help you choose the correct power supply unit.

ham 30 suggests in response no5, that a more powerful PSU unit may only be needed if you are upgrading or adding new peripherals, I totally agree with this.

The most important factor in selecting the correct PSU is to take note of the wattage.

Follow this guide below:

COMPONENT POWER REQUIRED
Low to mid range video card 60W
High end video card 100W
Expansion card 10W
ATA hard drive 30W
SATA hard drive 20W
SCSI hard drive 40W
Optical drive 25W
Floppy drive 5W
Cooling fan 2.5W
Motherboard 35W
256 MB RAM 15W
High end CPU 100W
Low end CPU 50W
LED 1W

The total wattage of all your peripherals installed in your system should not exceed the wattage of the PSU unit.

This will give you a guide of what you need.