Temperatures & Acoustics / Power Consumption
Temperature Analysis
For all temperature testing, the cards were placed on an open test bench with a single 120mm 1200RPM fan placed ~8” away from the heatsink. The ambient temperature was kept at a constant 22°C (+/- 0.5°C). If the ambient temperatures rose above 23°C at any time throughout the test, all benchmarking was stopped. For this test we use the 3DMark Batch Size test at its highest triangle count with 4xAA and 16xAF enabled and looped it for one hour to determine the peak load temperature as measured by GPU-Z.
For Idle tests, we let the system idle at the Windows 7 desktop for 15 minutes and recorded the peak temperature.
Our HD 7970 GHz Edition sample didn’t exhibit the best temperatures we’ve seen but they were still well within the realm of acceptability. The discrepancy between this card and the previous model likely comes down to differences between samples and the higher clock speeds of the GHz Edition.
Acoustical Testing
What you see below are the baseline idle dB(A) results attained for a relatively quiet open-case system (specs are in the Methodology section) sans GPU along with the attained results for each individual card in idle and load scenarios. The meter we use has been calibrated and is placed at seated ear-level exactly 12” away from the GPU’s fan. For the load scenarios, a loop of Unigine Heave 2.5 is used in order to generate a constant load on the GPU(s) over the course of 20 minutes.
This is one area where the latest high end AMD cards have traditionally fallen behind NVIDIA and the GHz Edition continues this dubious tradition. Luckily, we expect most board partners’ cards will feature custom coolers so you won’t have to worry about excess noise….hopefully. We do however recommend you stay away from the reference cooler if you value a quiet computing experience.
System Power Consumption
For this test we hooked up our power supply to a UPM power meter that will log the power consumption of the whole system twice every second. In order to stress the GPU as much as possible we once again use the Batch Render test in 3DMark06 and let it run for 30 minutes to determine the peak power consumption while letting the card sit at a stable Windows desktop for 30 minutes to determine the peak idle power consumption. We have also included several other tests as well.
Please note that after extensive testing, we have found that simply plugging in a power meter to a wall outlet or UPS will NOT give you accurate power consumption numbers due to slight changes in the input voltage. Thus we use a Tripp-Lite 1800W line conditioner between the 120V outlet and the power meter.
These numbers need some explaining since according to AMD’s documents, both the HD 7970 and its GHz Edition share the same 250W power envelope. Digging a bit deeper into each card’s documentation reveals some difference though. The HD 7970 released six months ago listed 250W as its max board power, referring to the peak amount the ASIC would draw at one time. The GHz Edition meanwhile lists 250W as its “typical power draw” rather than peak so expect it to actually draw more power than its predecessor. Nonetheless, the numbers are quite good considering the core is operating at 1050MHz during this test and the memory has been pushed to 6Gbps.