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View Full Version : Running a video card without enough amperage



Exershio
July 22nd, 2009, 03:28 AM
I'm thinking of buying an nvidia 6600gt to replace my radeon 9550 in one of my older systems, however, nvidia recommends 300w minimum (mine's 350w, so that's fine) and I think they recommend 18 amps on the 12v rail (not sure). My power supply only supplies 12 amps on the 12v.

What exactly would happen if I were to put this video card in my computer? Would it run slower, crash a lot, or just not work? The reason I'm asking is because I've seen a few people post on other message boards saying they have run that same video card with only 10a on the 12v, which is even lower than mine.

I don't really want to upgrade my PSU (not worth the money for this system), so if it won't work well, I probably just won't buy a new card at all. So what exactly would happen?

Yes
July 22nd, 2009, 03:30 AM
I was under the impression that if the card doesn't have enough power, it simply won't boot. I'm nearly certian it won't just not perform as well.

philcamlin
July 22nd, 2009, 03:35 AM
I was under the impression that if the card doesn't have enough power, it simply won't boot. I'm nearly certian it won't just not perform as well.

your right

i had too meny cards in my dell without upgrading the power supply and they just dont start and arent recognised :popcorn:

if its being recognised its being fed enough power

Marlonsm
July 22nd, 2009, 03:40 AM
You'd better choose other card. I think some newer, but low end card would be better, as it performas about the same as older mid/high end cards, but use less power. Maybe a 7300Le. Or an 8200 (I'm not sure it there is an off-board version of this one)
You can idientify those cards by having a higher first number (7, 8, 9 for geforces, HD 2, 3 or 4 for Radeons) but a lower second number (2, 3 or 4).

Whiffle
July 22nd, 2009, 03:41 AM
Two thoughts on this:

First, what kind of power supply? If its a cheapo one, then its possible that the rated amps are not correct, or exact, or are exaggerated. But assuming they are correct, you're still 6 amps/36 watts short on the 12V rail. I think that a few different things could happen. It could simply flake out when you put some demand on it, due to the voltage dropping when you pull more power. Or, the power supply could chug along happily for a while, and then die on you. Or, it could work fine indefinitely. Its really hard to tell just by the numbers.


Second, how are you going to be using it? Is it going to be doing alot of gaming? Surfing the internet? Running Compiz? If its not going to get used heavily (which is pretty much just gaming), then its not going to be drawing full power all the time, and then it might be ok.

A card probably won't boot if it doesn't sense 12V at its power inputs, but that doesn't necessarily mean the power supply can provide all the power that its looking for once its under load.

jerrrys
July 22nd, 2009, 03:41 AM
http://www.xbitlabs.com/articles/video/display/geforce6600gt-oc_3.html

http://www.xbitlabs.com/misc/picture/?src=/images/video/geforce6600gt-oc/6600gt_power_table-b.gif&1=1

Exershio
July 22nd, 2009, 03:48 AM
http://www.xbitlabs.com/articles/video/display/geforce6600gt-oc_3.html

http://www.xbitlabs.com/misc/picture/?src=/images/video/geforce6600gt-oc/6600gt_power_table-b.gif&1=1

Thanks for those links. so apparently it consumes about 4amps on the 12v line. But that's PCI express, I was looking at the AGP card. Would the load be significantly different? Now my only problem is figuring out how much my other compontents consume. :P