Overclocking and Power Consumption
All four graphics cards participating in our today’s test session belong to pretty high-performance solutions and three of them are pre-overclocked by the manufacturers. Nevertheless, we decided to find out if we could squeeze a little more out of them and undertook an additional overclocking session. The software power management technology available on Asus EAH4890 cards was off, so that all the testing participants could be in equal testing conditions. GeForce GTX 285 doesn’t support any technologies like that yet and may never acquire one for the voltage regulator circuitry with Intersil ISL6327 controller.
Either way, we managed to obtain the following results:
EVGA GeForce GTX 285 FTW
Taking into account the already existing overclocking, it is a pretty good achievement for the GPU and quite mediocre for the memory.
Zotac GeForce GTX 285 AMP!
Zotac solution proved a little more confident during overclocking having outperformed EVGA graphics card in memory frequency and main GPU domain frequency. However, it couldn’t surpass the 1600MHz bar for the shader speed. It is really hard to draw any final conclusions: both products overclock pretty similarly. In fact, they overclock similarly poor, considering the factory overclocking and extreme complexity of the G200b.
Now let’s move on to Asus EAH4890:
Asus EAH4890 couldn’t repeat the success of PowerColor HD4890 Plus and conquer the 1GHz barrier. Memory overclocked even less – only to 1050 (4100) MHz vs. 1200 (4800) MHz on PowerColor solution.
Asus EAH4890 TOP
As for Asus EAH4890 TOP, it did better: it was only 20MHz short of the sacred 1Ghz barrier, while the memory worked stably at 1150 (4600) MHz. Nevertheless, PowerColor HD4890 Plus remains an undefeated overclocking leader among ATI Radeon HD 4800 models.
Since our today’s review is devoted to the performance comparison between Radeon HD 4890 CrossFireX and GeForce GTX 285 SLI configurations, we decided not to test single graphics cards in overclocked mode, because we have already performed these tests for both: GeForce GTX 285 as well as Radeon HD 4890, and the results of these tests are very well familiar to our readers.
As for the power consumption, our current testbed doesn’t allow us to measure this parameter for two cards working in multi-GPU mode. Therefore we will only provide the numbers obtained as a sum of power consumption measurements for single graphics cards in 3D mode, because in 2D mode one of the cores is idle.
Actual numbers may be slightly different from the ones mentioned above, because even in 2D mode the power consumption of the secondary card never gets down to 0. Nevertheless, it will give you an idea of the power consumption levels in contemporary multi-GPU systems.
Of course, the leader is the triple-GPU Radeon HD 4870 3-way CrossFireX system. It is far ahead. However, the Radeon HD 4890 CrossFireX tandem consumes even a little less than a single Radeon HD 4870 X2. GeForce GTX 285 SLI is pretty power-hungry, but even despite the transition to 5nm process we didn’t expect anything else from a pair of G200b working in a maximum configuration at 648/1476MHz frequencies. You absolutely must have a powerful high-quality PSU in a system like that, although it doesn’t make sense to hunt for 1kW power supplies, even if you have Radeon HD 4870 3-way CrossFireX configuration. At this point we would like to wind up our theoretical part and move on to the practical performance tests.