How We Test
For comparison we’ve included the results from the HD 4870 X2's reference cooler to easily see how much better the aftermarket model on test is. If we've tested previous aftermarket coolers for the card in question, we'll also include those results in addition to some price to performance comparison break downs.
Where GPU coolers have alternative fan speeds, we’ll test at both the lowest and highest fan speed settings and recorded idle and load delta T results (see below) for each setting to give you some idea as to how much performance is affected.
When you’re in a gaming session there are peaks and troughs in demands that are put on your GPU. These can be in the form of dying and getting a loading screen, messing around in the menu system or simply travelling around part of a map where there aren't any explosions of other pwnage to render. During these stages, your graphics card cooler will dissipate any excessive heat that was built up during more graphically periods of game play.
For this reason, we test by loading up a level of Crysis in DirectX10 mode at 1,920 x 1,200 with 4x AA and leave it as it stands, resisting the urge to jump on and start playing. Every time the character is killed, the game loads again automatically from the last save point and the cycle is started. This process replicates the peaks and troughs of a gaming session. We leave it for an hour till the temperature has stabilised and then compare the delta Ts.
Delta T is the difference in °C between the ambient temperature and the recorded temperature of the hardware, in this case the GPU. We use RivaTuner
to take temperature readings of the GPU. RivaTuner creates a graph on the fly so we can leave things running and look back over the direction of the test and see the peak temperature.
A multimeter thermal attachment probe was used to take the ambient air temperature three inches away from the case's primary intake location. Delta T is a more accurate and comparable method of recording temperature because the ambient room temperature fluctuates from day to day.
Intel Core i7 Test System
CPU Intel Core i7 940 processor (operating at 3,709MHz – 22x168.6MHz)
Motherboard MSI Eclipse SLI motherboard (Intel X58 Express with three PCI-Express 2.0 x16 slots)
Memory 3x 2GB Corsair TR3X6G1333C9 memory modules (operating in dual channel at DDR3 1,349.4MHz 9-9-9-24-1T)
Storage Seagate Barracuda 7200.11 250GB SATA hard drive
PSU Corsair HX1000W PSU
Software Windows Vista Home Premium x86-64 (with Service Pack 1); Intel inf 184.108.40.2067 WHQL.