How do you spec out a power supply

[SilverLock]

How do you determine what size power supply you need for a system?

 

[klah]

You can use this: AMD Builders Guide For Desktop/Server Towers pages 12-13 "Calculating System Power Consumption".

Although most people just buy a high-quality 300W+ PSU and call it a day.

 

[SilverLock]

Thanks... though most of what is there went over my head on the quick glance I did... it will be useful if I read it completely.

At least I should be safe with a 380W from Antec.

I will have:

D865GRH Mainboard
PIV 3.0 Ghz 800FSB
Sound Blaster Audigy
2 Seagate Barracuda IV 60GB drives
1 DVD drive
1 CDR-W
1 External Zip Disk - PC powered
2 120mm fans

Most likely a 9600pro video card but want the room to add a 5900 or 9800 which require power from the PS and MB.

Anyone think the 380 won't be enough?

 

[FPSguy]

You might want to use the "power supply online calculator". If you want to understand how to do the calculation yourself I suggest reading the FiringSquad article linked at the bottom of the calculator. It spells it all out pretty nicely.

 

[SilverLock]

Looks like a great tool, but I am not positive of the results. I got a result of 510W power supply, and don't see myself has having a power hungry machine.

[edit]
Ok,... redid the tool after reading their article. The tool should be more clear in the ram selection area...

If you have 2 sticks of 512 ram - you put in 2 right? With the 128 they have next to it it almost makes it seem as though you should put in 8.

 

[SilverLock]

Damn... now I have found two other power supply calculators and all three with the same information have given me different answers.

Though the Power Supply I am looking at is the Antec True Power 380 and it has been reviewed very highly I am nervous because two of the calculators came up with my needing around 430W total.