GeForce 6800 GS: Battle for Watts

Power consumption has become a crucial parameter of any modern graphics card and we of course checked how much juice NVIDIA’s new product needs. Officially, the GeForce 6800 GS can eat up to 70 watts of power at maximum, but this is a purely theoretical number, hardly achieved under real conditions. We checked the power consumption of the card on a special testbed configured like follows:

• Intel Pentium 4 560 processor (3.60GHz, 1MB L2 cache)
• Intel Desktop Board D925XCV
• PC4300 DDR2 SDRAM (2 x 512МБ)
• Samsung SpinPoint SP1213C hard disk drive (Serial ATA-150, 8MB buffer)
• Microsoft Windows XP Pro SP2, DirectX 9.0c

The GPU was put to test by running the third 3DMark05 subtest in a loop in 1600x1200 resolution with enabled 4x FSAA and 16x AF. We performed the measurements with a digital multimeter Velleman DVM850BL (its 0.5% accuracy suits well for our purpose). And here are the results:

The high frequencies and the 256 megabytes of onboard memory must be fed amply: the peak power consumption of the GeForce 6800 GS is high, closely approaching that of the GeForce 6800 GT. Even the 0.11-micron tech process couldn’t help the new graphics card much. The RADEON X1600 XT consumes 13 watts less, but it has a 0.09-micron GPU, only 4 texture-mapping units, and 4 memory chips (the GeForce 6800 GS carries eight memory chips). Curiously, the new card almost does not use the 3.3V power line, consuming a mere 0.1W from it. This is a characteristic feature of the PCB and power circuit of the GeForce 7800 GT we mentioned in our NVIDIA GeForce 7800 GT review .

Overall, our expectations about the power consumption of the GeForce 6800 GS came true. The card requires about 55W under load, i.e. about the same amount as the GeForce 6800 GT needs. The new card is just a little worse than the RADEON X800 XL in this parameter, and noticeably worse than the newer RADEON X1600 XT. On the other hand, the power consumption remains at a reasonable level, not exceeding even 60 watts.

Theoretically speaking, the card could do even without an external power source, but feed through the PCI Express slot alone, as the ATI RADEON X800 XL with a slightly lower power consumption does, for example. Most likely, this was not implemented due to technical reasons: the power circuit borrowed from the GeForce 7800 GT probably must have an external power source. This should positively affect the stability of operation and the overclockability of the GeForce 6800 GS, by the way.