G70's Power Consumption

[ADGC]

It was stated on page 20 in Anandtech's article NVIDIA's GeForce 7800 GTX Hits The Ground Running that it would be difficult to directly measure the power draw of the GeForce 7800 GTX. However, I wonder if it might be possible to determine this indirectly by comparing the power consumption of a single GeForce 7800 GTX system to that of an SLI system and a system that lacks a GPU altogether.

 

[trinibwoy]

That's what B3D did.

Looking at the increase in system power utilisation with the 7800 GTX we see that there is an extra 108W of peak power utilisation, which may give an indication as to what a single board may be drawing.

 

[ViRGE]

Keep in mind it's not 100% accurate. Under that method, you're actually seeing the additional wattage going in to the power supply, but not just what the card is drawing. Since no power supply has 100% effeciency, actual power usage could be anywhere between 65%-85% of what the difference against the power supply is. A good guess on that mark then would be that the 7800GTX's power consumption is 75% of that 108W difference, for a value of 81 Watts. Taking in to account Xbit already ran precise power benchmarks of the 6800U, which pegged said 6800U at 72W, our guesstimated number is still too high since the 7800GTX draws less power than the 6800U, so actual power usage is likely in the 60W range.

 

[Goi]

How about tapping into the molex power connector/PCI-e power connect and the AGP/PCI-e slot power pins? Aren't these the only pins where the video card gets power?

 

[ViRGE]

Originally posted by: Goi
How about tapping into the molex power connector/PCI-e power connect and the AGP/PCI-e slot power pins? Aren't these the only pins where the video card gets power?

That's exactly what Xbit did. It's just really hard to do.

 

[Goi]

Thanks ViRGE. Apologize for not reading your post completely. The link was right there. That's an interesting, and probably the most accurate way of measuring power externally. I found the tables on exact power consumption particularly interesting. Also, why does a 6800GT that's clocked at 420/115 consume less power than a stock 6800U? Aren't they basically using the same GPU and board design? The only thing I can think of is the different fan being used - the 6800U may have a higher powered fan, but that doesn't explain the ~8W difference.

 

[Mirko]

Originally posted by: Goi

Also, why does a 6800GT that's clocked at 420/115 consume less power than a stock 6800U? Aren't they basically using the same GPU and board design? The only thing I can think of is the different fan being used - the 6800U may have a higher powered fan, but that doesn't explain the ~8W difference.

The Ultra have 1,45V and the GT have 1,35V. That why people put in new bios for higher volts.