How to compute POWER SUPPLY requirements.. Do you agree?

[VBboy]

According to this, my power supply requirements would reach 350, plus a few extra watts just in case (so 400 watt total, whoa)...

Do you agree with this information? :

AGP video card - 20-30W
PCI video card - 20W
AMD Athlon 900MHz-1.1GHz - 50W
AMD Athlon 1.2MHz-1.4GHz - 55-65W
Intel Pentium III 800MHz-1.0GHz - 30W
Intel Celeron 700MHz-900MHz - 25W
ATX Motherboard - 30W-40W
128MB RAM - 10W
256MB RAM - 20W
12X or higher IDE CD-RW Drive - 25W
32X or higher IDE CD-ROM Drive - 20W
10x or higher IDE DVD-ROM Drive - 20W
SCSI CD-RW Drive - 17W
SCSI CD-ROM Drive - 12W
5400RPM IDE Hard Drive - 10W
7200RPM IDE Hard Drive - 13W
7200RPM SCSI Hard Drive - 24W
10000RPM SCSI Hard Drive - 30W
Floppy Drive - 5W
Network Card - 4W
Modem - 5W
Sound Card - 5W
SCSI Controller Card - 20W
Firewire Controller Card - 10W
Case Fan - 3W
CPU Fan - 3W

Taken from UpgradeSource.com

 

[MasterQ]

The #'s may be right at PEAK usage.... though I wouldn't say that's exactly going to be the requirement for the system... Those #'s are with each device peaked in use and running... the scenario in which each component is working is probably never going to happen...

I.E. If your floppy is not reading/writing no power is used... same with hard drive, CD/DVD/CDRW, NIC, Modem, Sound card... etc... you get the idea...

 

[Duvie]

I agree...This is an unreal scenario and a 350 would be most likely fine...

Mine calculated at like 280watts and I have had a 250 work just fine with a tbird 1100mhz system...Not all pS's are created equal and some will not have continuous high throughput to take a peak of multitasking and multiple devices in operation.

 

[MplsBob]

You are missing one important point.

Your power supply puts out several different voltages. It is theoretically possible to fail because you have maxed out the capacity of just one of the voltages.

I suspect this is a much more involved issue than one would initially think. Also, throw in the factor that it would be unusual to have all of your hardware simultaneously inflicting max consumption. MasterQ raised this issue.

I would like to see a well written article on this issue.

== RANT ==

I am fairly firmly convinced that 225-250 watts OF AN AMD APPROVED POWER SUPPLY will run most systems just fine regardless of cpu speed. For reasons that escape me, there are a lot of people who are convinced you have to have a 430 watt power supply if you are going to run at 1400GHz. These same people also consider the AMD "approved" list as irrelevant.

There is a lot more to a power supply than just WATTAGE. How much noise rides each voltage. How well does it regulate. etc. Some of these issues are addressed on the AMD site.

 

[VBboy]

Ok, maybe only if all the devices are running would you reach that max. power consumption. But what if you want to add a TV tuner or a tape drive with a zip drive? Having to buy another power supply then would be more expensive than just buying a more powerful one now..

Also, who knows what your next AMD cpu will eat. 100 watts? maybe more..

As long as the power supply is certified, is it worth paying an extra 20% to get an extra 100 watts? I would do it just so I can keep this PSU for my next PC (something I couldn't do with my outdated and outpowered 250 watt weakling).