PSU vs Graphics Card Calculations - 9800 GT and 400W PSU.

Dave_The_Sheep

Buying a new card as a temporary replacement until I can get a new PC in Autumn/Winter. Kinda settling for a 9800GT, since the 4850 needs a 450W supply, which I can't give it. I have a 400W PSU, dual rail 12v1/v2 of 14A and 15A.

My PSU:


Thats enough for this, right:

http://www3.pny.com/9800-GT-EE-1024MB-PCIe-P2860C331.aspx#Specifications

"A minimum 400W or greater system power supply (with a minimum 12V current rating of 26A)"

From what I can see, the dual 12V rails at 14A and 15A should give me just enough juice for the 26A requirement right? Its the calculations side of things if the other rails are maxxed out that I don't know enough about to be able to make up my own mind.

The 400W is just enough, but its the Amps I'm worried about before buying it.

marco_polo

It is not a great PSU but it should be just fine for a 9800GT. As far as I can see the rated TDP for the 9800GT is roughly 105W which works out at a max possible draw for the card itself of about 105W/12V = 8.75A.

GPU manufacturers greatly overstate their PSU requirements, presumbly to reduce the number of support issues relating to crappy PSU they have to deal with.

The 26A is a (overtly) cautious recommendation that also very generously accounts for the possible power draw from the rest of the components in the system.

Presuming that your PSU can deliver close to its rated specs, and the rest of your system does not include a very heavily overclocked quad and a half dozen or more hard drives, there should be no problems whatsoever.

Dave_The_Sheep

marco_polo wrote: »

It is not a great PSU but it should be just fine for a 9800GT. As far as I can see the rated TDP for the 9800GT is roughly 105W which works out at a max possible draw for the card itself of about 105W/12V = 8.75A.

GPU manufacturers greatly overstate their PSU requirements, presumbly to reduce the number of support issues relating to crappy PSU they have to deal with.

The 26A is a (overtly) cautious recommendation that also very generously accounts for the possible power draw from the rest of the components in the system.

Presuming that your PSU can deliver close to its rated specs, and the rest of your system does not include a very heavily overclocked quad and a half dozen or more hard drives, there should be no problems whatsoever.

Thanks for the information. No, nothing overclocked that I know of, dual core CPU, only the one HD.

I thought it wasn't the best alright, but its the one that came with the package. When I'm building my own rig, I'll get something a little more high quality.

Hopefully nothing will explode when I'm playing games on it.

marco_polo

NorthQ wouldn't have the greatest reputation when put under pressure, but that setup shouldn't be able to push anywhere near to its limits with a 9800GT.

Just promise to throw it away when new PC time comes.