Build-A-Rig Round 1, Zotac vs. Corsair: The $1500 PC Showdown

Power Consumption and Thermal Performance

Our final set of evaluation criteria for our Build-A-Rig systems is power consumptions and temperatures. Given the sometimes disparate component choices between Zotac and Corsair, we’re expecting to see some significant differences in power consumption here. Corsair went with more powerful components than Zotac, but their power consumption and overall thermal load should be higher than the Zotac system as a result.

Also throwing a wrench in things is of course the differences in cases. Both Zotac and Corsair went with low-to-mid range mid-towers, but due to differences in build layout, mounted coolers, and airflow, that will also have an impact.

With both systems based off of a Core i5 processor and GeForce GTX 900 series GPU, idle power consumption at the wall isn’t going to vary greatly. What difference we do see is mostly down to the PSUs; the Zotac system features a larger PSU, which all things considered is going to be a bit less efficient at idle than the Corsair PSU.

Load power consumption on the other hand isn’t too far off from what we’d expect. The most surprising result here may be Prime95, our CPU stress test, which finds that the Corsair system is drawing some 31W more at the wall. On paper both i5 CPUs should be close in power consumption, but in practice the lower clocked Core i5-4460 CPU in the Zotac system is going to draw less power than the top-tier Core i5-4690K in the Corsair system, leading to what we see here.

Otherwise once the GPU comes into play, the difference in power consumption between the two systems ramps up significantly. The GTX 980 Ti in the Corsair system has a TDP nearly 100W higher than the Zotac GTX 970, and under FurMark in particular it makes itself apparent. Even Crysis 3 sees a 60W difference at the wall, going hand in hand with the Corsair system’s better GPU performance.

So what does this do for temperatures? Both systems feature Corsair closed loop liquid coolers, with the Zotac system using the larger of the two, an H100i GTX. The bigger difference is that the Corsair system features a blower-type video card, whereas the video card in the Zotac system is open air, and as a result relies on the airflow from the CPU cooler to exhaust the bulk of the heat.

At idle CPU temperatures are similar, but under load we see the result of the Zotac build’s larger cooler and lower power processor. Granted for our CPU workload we’re running FurMark, about as close to a sadistic workload as one can get, but these also represent the hottest temperatures one should see. In any case the Zotac system’s CPU is some 13-16C cooler than the Corsair system’s, due to the difference in build configuration.

GPU temperatures are also in Zotac’s favor, again due to the lower power consumption combined with larger coolers, and in the case of the video card an open air design. The GPU is not significantly affected by the CPU, so what we see is the full impact of FurMark on each card. Ultimately the GTX 980 Ti reaches its default thermal limits, as we’d expect for a reference card, while the Zotac system and its Zotac GTX 970 remain much cooler thanks to its open air cooler. But in return the Zotac card is offloading some of the cooling workload to the chassis, so it’s a good thing the Zotac system features the larger H100i GTX 2x120mm CLLC.