Power Consumption, Heat and Overclocking
Power consumption was measured using a simple AC power meter. Keep in mind that the full system power consumption is measured (not including the monitor). Full GPU load was achieved using the PT Boats: Knights of the Sea benchmark. In my experience, this puts a substantial and consistent load on the GPU.
With the HD4850 leading slightly at idle and the 9800GTX+ leading slightly at load, both cards display nearly identical consumption. What I find most interesting is that the 9800GTX+ calls for dual PCIe power connectors. Why would this be necessary when it has a lower peak power draw than the HD4850? This is certainly not a big issue for those with quality modern PSUs, but it certainly gives the wrong impression about the 9800GTX+.
Much like the power consumption, GPU temperatures were very close between the two cards. NVIDIA’s 9800GTX+ reference cooler is very effective. It should be noted that the HIS HD4850 uses the IceQ dual-slot cooling solution, which is why it fairs so well against the 9800GTX+ in our comparison. The single-slot HD4850 reference cooler is not able to maintain temperatures in this range.
When it comes to overclocking, the Zotac 9800GTX+ AMP! Edition is no slouch. We were able to obtain a very impressive 838MHz on the core and an extra 100MHz on the GDDR3. This is especially impressive when you consider the card’s factory overclock. It’s a pity that Zotac didn’t clock the card closer to 800MHz by default, as clearly the card is capable. To obtain the above result, we had to keep the shader clock speed unlinked and below the 2050MHz mark to maintain stability. The card’s fan was forced to 100% for this overclock.