Buying a PSU - Advice please..

  Whaty 07:48 12 Jan 04
Locked

I need a need a new PSU. The 'expert' at PC World told me that if I buy a 400W PSU it will fry my MB but I don't understand this. Surely the system (drives, cards, MB etc) will only draw what it needs from the PSU and therefore, the higher Watt rating will simply give my computer a better capacity for expansion and will not 'fry' anything.?

My current PSU is 200W. The computer is 4yrs old and is a P3 450, Gigabyte MB, 3DFX graphics card, SB 64 PCI card..

My PSU just gave up for no apparent reason in a puff of smoke, you can see a small area of the PCB in the PSU is burnt but the fuse didn't blow. What are the chances of damage to any of the components in the computer, visibly everything looks fine..

  Jester2K 07:56 12 Jan 04

"The 'expert' at PC World told me that if I buy a 400W PSU it will fry my MB but I don't understand this. "

He's talking out of his hat.... You're right the components draw what they need.

"What are the chances of damage to any of the components in the computer, visibly everything looks fine.. "

You won't know until you try. Seen it leave everything intact, seen it blow everything except the case. Chances are most things will be OK though.

  GibsonSt19 09:10 12 Jan 04

click here (this is one I bought a while back and is serving me well.

click here for the 400w version.

Hope that helps!

  Gongoozler 10:31 12 Jan 04

I recently fitted a Qtec power supply like the one suggested by GibsonSt19, and was very impressed by the quality for such a reasonable price.

Regarding the "expert" advice from PC World. That is absolute rubbish. The most basic law of electrics is "Ohms Law". This says that the current taken by a device depends only on the applied voltage and the resistance of the device. In the case of your power supply, as long as the supply is capable of supplying the power, the device will take the current it is designed for. If the current demand is too high, the power supply will no longer be able to provide it, and either the supply voltage will fall or the PSU will protect itself and shut down. The only exception in a computer power supply is that there may be a minimum load you can put on the supply below which it is unable to regulate the voltages, and will probably shut down, but this is a very low limit not likely to be met in any real situation. If you think about it, your computer is running from power generated by a supply of many Megawatts, but that doesn't cause it to blow up.

  BeForU 10:33 12 Jan 04

i have the 550W version and it does wonders. Brought it back latest May for £17 as well. Guess the price has gone up but not much. Such a high quality PSU for such a good price as well.

Whaty, looking at those specs, i think at least a 300W psu would be fine so you dont need really high ones.

  Whaty 18:09 13 Jan 04

Thank you for the replies, I think I will go for the Q-Tec, found a few reviews and they are all good apart from suggesting they have noisey fans and (slightly) short leads.? I live near Manchester and there is a computer fair every Saturday (supposed to be the largest in Europe.?) so I'll have a drive over there this weekend and see what's available.. Just hope there is no other damage to the machine now.. Thank you again for all your help.

  Rayuk 18:20 13 Jan 04

If you live close to Manchester
North Side-visit Planet Micro
South Side-visit Micro Direct/ Aria
Just up the M61 -visit Scan
Unless of course you are taking this opportunity to visit Bowlers.

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