Very simple question about PSUs

I am interested in getting a computer with an HD 4650 1GB. The requirements for the card are 400W. The computer only has a 300W PSU. The tech support guy assured me this wouldn't be a problem, but it seems like simple math that this would be a problem. Likewise, a Dell computer I was interested in had a 4850 with a requirement of 450W, but the Dell only had a 350W PSU.

Can someone explain why this is, and if it's really that big of a deal?

While a 300W is cutting it a bit close, you'll be fine.

Video card manufacturers tend to inflate the value needed for power consumption of their video cards just to be on the ultra safe side. They want their video card to fit in a barebones PC running on a 300W with 1 hard drive and 1 CD drive as well as a mega PC with dual SLI, 4 hard drives, 3 cd drives, interior lights, overclocked memory and CPU, and all the works.

What they SHOULD do is list peak power consumption of the video card - but most consumers arent aware of how much power their systems draw.

Those are 'safe' requirements in that the manufacturer feels that every 400W power supply will provide ample juice to power the card and the rest of the computer. Depending on if the power supply delivers enough amps and you don't have multiple HDDs, CD Drives, fans, etc sucking on it, you could use a supply with a lower max output. Although in this case 300W might be pushing it - you don't want to get too close to your PSUs max output rating.

I forget the address, but one website offers a pretty handy power usage estimating program that kept pretty well up-to-date with the latest equipment.

Thanks!

For a bit of reference, here is the 4650 computer (300W), and here are the specs of the 4850 dell (350W):

Studio Mini-Tower
Intel® CoreTM 2 Quad Q8300 (4MB L2, 2.5GHz, 1333FSB)
Operating System Genuine Windows Vista® Home Premium Edition SP1, 64-Bit
8GB Dual Channel DDR2 SDRAM at 800MHz - 4DIMMs
Dell Consumer Multimedia Keyboard and Laser Mouse
18.5" Dell IN1910N HD Monitor with VGA port and cable
ATI Radeon HD 4850 512MB
640GB Serial ATA Hard Drive (7200RPM) w/DataBurst CacheTM
Floppy Drive and Media Reader Integrated 16-in-1 Media Card Reader
Network Card Integrated 10/1000 Ethernet
No Modem Option
16X DVD+/-RW Drive
Integrated 7.1 Channel Audio

Think what you will about either company, they offer to include those cards only because they've tested and are 100% sure its going to work.

Think what you will about either company, they offer to include those cards only because they've tested and are 100% sure its going to work.

chefkw

Just because it works initally doesn't mean it is a good idea nor that it won't have problems down the road...