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What's the highest PSU wattage I can go for an Intel D865PERL motherboard (Pentium 4)?

I have an Intel D865PERL motherboard:

with the following processor: Pentium 4 CPU 2.80 GHz, 2.79 GHz, 1.00GB RAM

I only have a 300W PSU and I clearly need more, because the video card says so.

Is it safe for me to upgrade to a 550W PSU? (Or, what's the highest PSU I can go for?) Won't it fry my motherboard? I normally leave my machine on for months.


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up vote 3 down vote accepted

The wattage of your power supply indicates the power load it can supply. It does not mean there is more current running through your motherboard. You can put any standard PC power supply into that system.

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There is no upper limit on the wattage of the power supply which your system can use other than defined by chassis physical dimensional (mechanical) requirements. A power supply will only deliver the current pulled by the system and will not "push" high current through the system.

One thing to keep in mind is many power supplies are inefficient at a light load. For example, if you get a 1kW supply and are only pulling 250W (25% load), it could be 60-70% efficient and actually waste more power than an appropriately sized one. One way to avoid this is to get an 80 PLUS rated power supply which requires the PSU to be >= 80% at light, middle and heavy loads.

Image from Jeff Attwood's Coding Horror: When Hardware is Free, Power is Expensive:

alt text

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