Thermal Performance

To thermally test the cards we recorded GPU temperatures for each individual core using RivaTuner. Idle readings were taken at the desktop in Windows Vista 64-bit Home Premium with Windows Aero enabled, while the load reading taken while the GPU configuration was running our Crysis benchmark at 1,920 x 1,200 with 0xAA.

This is one of the most demanding tests in our benchmarking suite, and is sure to get those GPUs sweating. We didn't go higher because we felt that if we increased the load too much, some of the slower cards wouldn't deliver realistic numbers because they'd be bottlenecked in other ways.

All temperatures were taken with the cards cooled using only their standard stock coolers and running on our open air test benches, which have no additional airflow other than that present in the room.



Both the HD 4890 and the GTX 275 have plenty of cooling headroom for when (if, in our case) Summer arrives and the temperatures start to rise. Under load, the firmware on the GTX 275 dictates that the GPU can run at up to 90°C, and to achieve this the fan only spun at up to 55 percent speed.

ATI is more conservative with the operating temperature of the HD 4890, as under load the GPU never rose above 64°C with the fan spinning at a very noisy 36 percent (2,422 RPM).

Clarification

While it's true that the HD 4890 GPU is relatively cool, the card itself is hot. The heatsinks, the cooler backplate, even the PCB - all are very hot to the touch.

Of course, the purpose of a heatsink is to get hot, but considering the loud fan and the jet of hot air that comes out the back of the HD 4890 card, it's disappointing that nowhere near all of the heat is being sucked from the card, and that the card is still radiating lots of heat into your case.

The GTX 275 meanwhile does a better job of getting the heat from the entire card out the rear vent, though obviously it's not a 100 percent success rate and the card does still get hot. However, the GTX 275 card doesn't get anywhere near as hot as the HD 4890 card.