Card with one PCIe connector requires 40A?

[powder21]

So this is probably a n00b question, but a friend of mine bought a video card (ASUS HD7770-2GD5) before checking the power requirements. I had him send me a pic of the specs and it lists a 40 amp requirement for the 12V rail.

The only conclusion I could come to was that it was listing a requirement of 20A or higher on each 12V rail. However, my uncle who has built way more computers than I have, said that if that was the case, the card should have 2 PCIe power connectors. The card only has one. I have never seen a power supply rated at 40 amps on one rail.

I went ahead and recommended a OCZ 550W supply with dual rails rated at 25A each, however I'd like for someone to chime in on this as the conflicting info I'm getting has me wondering and I'd love an explanation as to whether or not my uncle is correct and why.

Thanks in advance!

 

[96Firebird]

The 7770 doesn't draw 40 amps, that would be 480W (40A*12V) to just the card alone. It probably draws closer to 10-15 amps, so any 450W+ PSU will be sufficient.

 

[Smoblikat]

The 7770 doesn't draw 40 amps, that would be 480W (40A*12V) to just the card alone. It probably draws closer to 10-15 amps, so any 450W+ PSU will be sufficient.

Any 300w would be suffecient.

 

[TemjinGold]

The 40 amp rec is for the WHOLE system, not just the card.

 

[frozentundra123456]

The 40 amp rec is for the WHOLE system, not just the card.

Even then AMD is very conservative in their requirements for power supplies. They list 400watt reqiurements for some low power cards that dont even require a 6 pin connector. Actually, I think the only "requirement" is the 6 pin connector. The watt rating is a suggestion I believe.

40 amps is in fact 480 watts as someone else stated. That is way overkill for a 7770 unless you are running something like an AMD cpu that requires 125 watts and/or are overclocking.
I would think you could run a 7770 and a 100 watt or less CPU with a good quality 350 to 400 watt power supply.

 

[fralexandr]

it is theoretically impossible for any single PCI-e 3.0 card with 1 6 pin power connector to draw 40 amps from the 12v rail at the moment
http://en.wikipedia.org/wiki/PCI_Express#Power
max theoretical draw would be 225W (at most 18.75A @12v) (a small portion might be on the 3v rail)

total system power draw of 250w on a llano A8 w/ 7770 for metro 2033
http://www.anandtech.com/show/5541/amd-radeon-hd-7750-radeon-hd-7770-ghz-edition-review/23

 

[powder21]

Arg! OK, thanks everyone. Below is the exact wording of the spec listed:

"A minimum 450W system power supply (with a 12V current rating of 40A)"

I can't believe I didn't remember that Watts equals amps x volts. I got caught up in the fact that the last card I bought had a minimum amperage rating requirement listed specifically for the card. God I feel dumb :-(