JB wrote:

>
> Thank you for your input Kony. I am sure you can do a power budget and
> allocate it per rail but that is not what I need.
>
> I am savvy on the engineering considerations but my gripe is with the
> ribbon- clerk type disclosure of power requirements.
>
> For example, the particular card whose requirement I mentioned as being
> 22A on the 12 V rail is an EVGA 8600GT. My gut feel is that the card
> does not need anywhere near that much current. In fact, IFhe link below
> gives the power dissipation for that card as being 30W, not the 264W
> implied by the requirement on the box. So, IF the numbers at the site
> are correct, the card itself needs 2.5 A.
>
> http://www.atomicmpc.com.au/forums.asp?s=2&c=7&t=9354
>
> Obviously EVGVA's intent is to tell the customer his total system needs
> that much capability on the 12V rail...a prognistication only a true
> seer should make. But that is not what they say so it's worse than no
> information at all AFAIC.
>
> BTW, that card is just one example, it's not one I intend to buy. I
> know other companies put similar requirements on the customer and think
> it's just sloppy work across the board. I don't think a user should
> have to buy a clamp-on ammeter and verify the ratings.
>
> When I get my components selected I will select a PS and then see what
> you folks think.
>
> Thank you.
>
> Mike
>

Xbitlabs measures video card power consumption, by using current shunts
on the slot. The 8600GTS is about 12V @ 3.75 amps total, so the 8600GT must
be a bit less than that. The card draws that current, partially through
the slot connector, and partially through the Aux connector on the end
of the video card. At this low current level, if they had wanted, they
could have drawn it all through the slot. Using an Aux connector is quite
conservative.

http://www.xbitlabs.com/articles/vid...8600gts_7.html

Even if the companies making the products gave out power estimates, they'd
probably be wrong anyway :-)

Paul