Power Supply necessary for my computer system?

Question

I'm a very confused.  I've used 2 wattage calculators (on line) and have come up with DRASTICALLY different wattage estimates.  So here is what I have for a system:
Biostar TA780G M2+ motherboard
AMD Phenon x4 9550 quad-core cpu
Ultra X-Wind Aluminum Socket K8/AM2 CPU Cooling Fan
4 x Kingston PC6400 800MHz 4GB DDR2
1 x 140mm case fan
EVGA GeForce 9500 GT Video Card (PCIe 2)
Seagate 160GB Serial ATA 7200/8MB/SATA-3G
no optical drive (I use a portable usb dvd/cd-rom drive with it's own power supply)
I use the Motherboard's on board audio and network cards

Currently I have a BFG 450 watt power supply that has no problem what so ever running this system.  and surprisingly the case is nice and cool.

I'm upgrading the video card to a XFX Radeon HD 4890.

one wattage calculator reports the wattage total (with new video card) as 281 watts, the other reports 586 watts.  So which one is closer to the truth?

btw the two calcualtors are:
http://extreme.outervision.com/PSUEngine
http://educations.newegg.com/tool/psucalc/index.html

Anonymous · Accepted Answer

The 281W is clearly lying, you used to get 200W with Pentium 4s, if I was in your situation I'd go for at least a 550W, I think the second site is more accurate. 

For the future where you might end up with multiple hard drives and faster components, I'd recommend a 650W if you can afford it

Nik · Answer

I couldn't calculate this for you but to be on the safe side go with the higher wattage and buy a PSU that out does the 500W calculator just to avoid damage or find your components online and they will tell you at the stores the component watt usage you can then list all these and come out with a total your self but don't forget all thecomponents like your CD/DVD drives as well.

Paul · Answer

If you really want to know how much wattage you are using buy or borrow a meter called a "Kill A Watt".  You just plug your computer into it and then plug the meter into the wall and you will get a direct readout of wattage being used.  I think mine cost about $25 but you can check around on the Web.  It's a handy little device to have around the house.

duhcoolies · Answer

By the looks of your system specs, I would say that the calculator which reports 586 watts is more accurate as 281 is way too low for newer systems. Only very old machines tend to go low as 281 watts.

Martin · Answer

For a XFX Radeon HD 4890 and all the stuff you has you will need a specialized psu (power supply unit) sli certificate by nvidia of at least 600W because you will need the extra pci-express auxiliary connectors which comes with that psu and the more amperage (more voltage = more amperage = better stability of your video card) it has than the standard ones. This power supply units are far more expensive than standard ones but you will ensure a great performance and almost no hardware problems (voltage related).

BestKept · Answer

Under load 586 watts would be more accurate for that setup. Go with a 600 watt+ P/S.

∞ Infinite ∞ ∞ Life ∞ · Answer

I think you should be fine with ur current set up.  Check the watts running it on a 12V rail to get the true power usage.

Mark N · Answer

Any 600W PSU with good amps on the +12V rail will do.  http://www.newegg.com/Product/Product.aspx?Item=N82E16817182150
This one has 74 amps on the +12V rails and not a bad price...

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Power Supply necessary for my computer system?

8 Answers