Do I need a power supply upgrade? Any suggestions?

  john74 02:55 31 May 2004

I have recently made some system upgrades in term of processor, extra RAM and an additional hard drive.

Spec post-upgrade:

Athlon XP 2800+ (Barton)
1 GB PC2700 DDR RAM (3 DIMMS in total)
Gigabyte GA7VAXP m/b
ATI Radeon 9700 Pro video card
2 x 7200rpm hard drives
2 case fans.

(I'm not into overclocking, and run the system at its normal specs.)

I currently have a Q technology 300W power supply (bought from This can supply 175W from the 3.3V and 5V rails, and 280W from 3.3, 5 and 12V.

The system runs very well, and is not unstable in any way, but I can't help thinking 300W is inadeqate?

Should I upgrade to a new power supply, even though system works ok?

Any suggestions of power rating and good models?

  antoni34 06:52 31 May 2004

I`m using a 400w PSU because I have in my system :
Athlon 2.4Ghz CPU
1Gb DDR memory
Gigabyte K400 mobo
Geforce FX5600 256Mb Graphic Card
1 Pioneer A105 4x DVDROM/RW
1 Samsung 48x24x48 CDROM/RW
4 x 80gb HDD
And running Windows XP Pro

I have never had a problem !!

Can`t recommend any PSU 2 buy, as I get my stuff thro` a mates PC shop.

"The system runs very well, and is not unstable in any way"

If it's okay, then it's okay. Maybe if you were to go for the latest graphics cards then you might find you 'need' the additional power.

Otherwise, a stable system is an enviable thing and it's quality of PSU that matters more than sheer power rating. Just enjoy it. :-)

  Doogie Howser 07:31 31 May 2004

I'm running a similar setup with the same CPU, only 512 RAM, 2 hard drives, CDRW and CDROM etc. I have a 350w PSU and haven't had any problems. I suspect you're worrying about nothing, especially if your system's stable.

  Jakey boy 07:54 31 May 2004

My main system is an HP Pavillion 7870, running on a 250w psu, for about 3 years now. Ram is fully loaded with 512mb, 2 HD's and DVD-R, CD-RW. Graphics card is nVidia GeForce FX-5200. It can be a little unstable, but I think that may be Win ME, rather than the PSU. Trust the above experts, if it aint broke......

  john74 01:29 02 Jun 2004

Thanks guys,

It's very true that quality of power supply matters more than absolute power output.

My Q technology 300W power supply can produce 175W from the 3.3V and 5V rails combined, with a total of 280W when the 12V rail is added in.

I also have a cheap Q-tec 400W power supply. It only produces an extra 5W from the 3.3V and 5V rails combined (180W), when compared to my 300W unit. The extra power comes largely from the 12V rail, which I believe is no use to power a faster CPU or more RAM, but only useful for lots of hard drives etc. From a CPU point of view there seems therefore to be little difference between these 2 power supplies, despite the fact one calls itself 400W!

  hugh-265156 02:43 02 Jun 2004

you have got it spot on john74.

a psu rated overall at 400w may not be as powerful as one of a lower wattage depends how the manufacturer quotes this.

amps output on each rail are important not overall watts output as this is shared by all the rails and not divided up the same in every psu of same need to look at the label.some manufacturers quote max not sustained power also.

+3.3 +5 and +12v rails are the important ones to look at for amps rating and how the watts are shared over them.

click here is a shows how labelling can be a bit deceptive click here

here is a little list of some psu`s and their output specs click here

ps. if your computer is stable then its fine.

  Tog 07:28 02 Jun 2004

If it ain't broke, don't fix it ;-)

  Mister Splendid 08:19 02 Jun 2004

I run an Asus A7V600 m/board, athlon XP 3200+, 1GB PC3200 ram, Geforce FX5900 128MB, DVD ROM drive, DVD RW drive and 2 WD Raptors all on a 300w supply with no problems.

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