Temperatures & overclocking
Temperature musings
We perform our testing on an open test-bed with a 120mm fan simulating case airflow.
| Graphics cards | PowerColor HD 4870 1GB PCS+ | Sapphire HD 4870 512MiB | PowerColor HD 4850 512MiB | eVGA GTX 260 FTW 896MB | Leadtek 9800 GTX+ 512MB |
|---|---|---|---|---|---|
| Ambient temperature | 23°C | 23.5°C | 25°C | 23°C | 23.5°C |
| Idle temperature | 46°C | 78°C | 77°C | 53°C | 53°C |
| Load temperature | 63°C | 90°C | 82°C | 71°C | 67°C |
| Ambient-to-load delta | 40°C | 67°C | 57°C | 48°C | 44°C |
For comparison, the temperatures for eVGA's GTX 260 FTW, at its heavily pre-overclocked levels, are provided in brackets, to show a worst-case scenario for the GTX 260.
The Radeon HD 4800 series had looked incredibly toasty compared to its NVIDIA rivals: with their coolers sacrificing lower temperatures to maintain quiet operation. PowerColor's PCS+, with its ZEROtherm cooler, goes some way to redressing the balance, offering far cooler temperatures. We observed a whopping 27°C reduction in the load temperature, whilst maintaining reasonable noise levels.
Overclocking
Cranking it up, the card ran to a maximum stable overclock of 830MHz core and 4,160 MHz memory.
These represent overclocks of 3.7 percent on the core and 12.4
percent on the memory, over the already pre-overclocked shipping
frequencies. These overclocks are pretty impressive, with the core
overclocking a little higher than our previous testing of Force3D's
reference design, found here,
but the memory achieving a little less. This is understandable given
both the higher density modules in use, and the limited cooling offered
by the small memory heatspreaders.
Looking back at the ET:QW test at 1,920x1,200 we see that PowerColor
card, at its shipping clocks, scored an average 75.33fps. When
overclocked this rose to 79.00 fps: a near-5 per cent increase.
