Test PSU under load

  Terry Brown 08:01 05 Jul 2006

Under normal office use, my computer runs OK, however when I am doing Video work the PSU gets hot and after about 40 minutees will shut my machine down.
The output (PSU) is marked at 550w, however I suspect it is less than that.
Is there any way I can test it under load.The voltages are all within range (even under load)-tested using multimeter in spare power plug and 12v reads 12.04, 5v reads 4.98.
How can I test the output wattage, many thanks

  rmcqua 08:43 05 Jul 2006

Not easy, without a dedicated power supply tester. You need some method for loading each separate ouput up to its maximum (so, for example, if your PSU's +5V DC output is rated at 10 Amps., you need a resistor or dummy load of approx. 0.5 Ohms) The same goes for each of your outputs. Then measure volts x Amps. for each output, add them together, and that will give you total Watts.
So, as you can see, quite complex and not really practical for most of us.
If you are really sure that your PSU is overheating and causing the computer to shut down, I can only suggest replacing the PSU. 550W should be OK for video work, unless your PC is a VERY high performance machine. I wonder what is the brand of your PSU? I suspect that its 550 Watt rating may be optimistic?
Good luck,

  vinnyT 10:36 05 Jul 2006

In a.n.others pc mag, they test psus on a yearly basis for efficiency, power output, etc.

They found that some psus were, as rmcqua says, rated optimisticly, eg one 55ow was actually only just over 300w.

  Terry Brown 14:03 05 Jul 2006

Thanks, It seems a lot of trouble to test a CPU, it might be easier just to buy a new one. Can you recommend a decent one as the prices vary greatly.
Thanks Terry

  vinnyT 14:49 05 Jul 2006

Seasonic is the one I would go for, but they are a bit pricey.

  Pamy 15:04 05 Jul 2006

you could look here for a tester

click here=

  woodchip 15:57 05 Jul 2006

You need special Gear, too expensive for one off. Can you put a bigger fan in the PSU or make some more holes in the intake side of it

  woodchip 15:59 05 Jul 2006

Also A Fan in the PCI card bay will divert some hot air direct to the outside, rather than it all going through the PSU. This hot weather do's not help, Try running with side off tower

  Fruit Bat /\0/\ 16:18 05 Jul 2006

If renewing a PSU check:

1. The physical size of your PSU, some are hard to replace due to being a non standard size.
2. The amount of power need from the PSU don't skimp

1. Physical Dimensions

Besides the specs and form factors, the physical dimensions are also important factors in selecting a compatible power supply. Here is an outline of the physical dimensions of most standard power supplies:

# ATX: 6x3.5x5.5", HxWxD. Most common. Uses 4 mounting screws.
# Mini-ATX: 5x3.5x5", HxWxD. Rare size. Uses 4 mounting screws. Can be used in a regular ATX case, but often not the other way around.
# MicroATX: 5x3x4", HxWxD. Use 3 mounting screws. Not interchangeable with ATX or miniATX.
# Flex ATX: Even smaller than Micro ATX. Various sizes according to case specs; often not interchangeable.

Use the data above to determine if a particular power supply would fit your case.

The quality of a power supply can be estimated by its weight. While this is not a true scientific or thorough measurement of the power supply reliability, it is nevertheless a very simple and easy way for ordinary PC users to estimate and compare the quality of a power supply.

2. Power supply calculator click here

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