What's the needed power for a graphics card?

Asked by haegenschlatt (122

) May 13th, 2010

I’ve gone about the process of building a computer- I’ve picked out parts, and I’m just about ready to order.

One thing that worries me, however, is if my power supply will be sufficient for my graphics card. My PSU is rated at 350W and the power supply calculator states a recommended power of 304W, but I don’t have a clue about the 12V lines, what they mean, or if they are adequate.

I plan to use a Radeon HD 4850.

Here is the information:
+12VA / 12A +12VB / 18A
+5V / 18A +5Vaux / 2A
+3.3V / 17A -12V / 0.8A

Combined power of +12VA and +12VB is 300W.
Combined power of +5V and +3.3V is 160W.

Will this run my graphics card or should I buy a new one?

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2 Answers

The 12v lines are used primarily for the drive motors and cooling fans. The electronics are powered from the 3.3v and 5v buses.

This being said – you can’t go wrong by having too large of a power supply, but you don’t want to get caught with one that’s too small. I would up your supply to 450 or 600 watts just to give yourself some breathing room. Most PSUs are at least 450W these days. Go here to find a selection.

IchtheosaurusRex (8681

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The 4850 will max out around 250W. I would guess you total power consumption under full load to be closer to 400–450W depending on your other components. A 550–600W PSU will keep you covered

arpinum (1989

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