Power Consumption, Temperature, Noise and Overclocking

The ATI Radeon HD 4850 is declared to have a peak power consumption of 110W. We checked this out using our special testbed with the following configuration:

• AMD Athlon 64 FX-55 CPU (2.6GHz)
• EPoX EP9-NPA+ SLI mainboard (Nvidia nForce4 SLI)
• PC3200 SDRAM (2x512MB, 200MHz)
• Western Digital Raptor WD360ADFD HDD (36GB, SATA-150, 16MB buffer)
• Chieftec ATX-410-212 PSU (410W)
• Microsoft Windows Vista Ultimate 32-bit
• Futuremark PCMark05 Build 1.2.0
• Futuremark 3DMark06 Build 1.1.0

We tried to use 3DMark Vantage to create a 3D load but this benchmark proved to load the card less than the first SM3.0/HDR test from 3DMark06. That’s why we adhered to our earlier methodology and tests. As usual, we ran the test at 1600x1200 with 4x FSAA and 16x AF. The Peak 2D mode is emulated by means of the 2D Transparent Windows test from PCMark05.

Here are the results:

Click to enlarge

The 3D mode result coincides with the number published by ATI Technologies. 110W is quite a lot, but the RV770 consists of as many as 956 million transistors. The Radeon HD 4850 is obviously an economic product. It consumes less power than the GeForce 9800 GTX that uses a less complex GPU with more modest specs. And it is far superior to the ATI Radeon HD 3870 X2 and Nvidia’s GT200-based solutions in this respect. The power consumption in the 2D and Peak 2D modes is quite high in comparison with the ATI Radeon HD 3870 but still reasonable. It is roughly comparable to that of the Nvidia GeForce 9800 GTX.

The load distribution is just what you could expect. The external PCI Express 1.0 connector is under the highest load in 3D mode – almost reaching 75W, the maximum allowable load. We wouldn’t be surprised to see per-overclocked versions of Radeon HD 4850 come with an 8-pin connector or with two 6-pin ones (like the Radeon HD 4870).

Notwithstanding the modest cooler, the card is not too hot. The GPU temperature is 62°C when idle and 86°C under 3D load. Well, the temperature is high under load, especially as we tested the card with the side panel of the system case removed. The card was very hot to the touch. In a cramped system case or under a higher ambient temperature the GPU may easily get even hotter. It is clear that the reference cooler of the Radeon HD 4850 is not meant for overclocking, but replacing it with something better shouldn’t be a problem. Thanks to the matching mounting holes you can use every cooler that supports Radeon HD 3870/3850 cards.

Next we measured the level of noise produced by the card with a digital sound-level meter Velleman DVM1326 using A-curve weighing. The level of ambient noise in our lab was 36dBA and the level of noise at a distance of 1 meter from the working testbed with a passively cooled graphics card inside was 43dBA (it is due to the Enermax Galaxy DXX EGX1000EWL power supply, which is not very quiet). Here are the results:

The new 19-blade fan affects the noise parameters of the new card, especially at a close distance, yet the card is barely audible among the other system components. If you’ve got a quiet system configuration, you may want to replace the reference cooler with something quieter, such as Zalman VF1000.

We tried to overclock the card using the appropriate option of the Catalyst Control Center. We managed to increase the GPU frequency to the highest permitted value – 700MHz. The memory chips sped up to 1100 (2200) without losing stability. We didn’t test the card at the overclocked frequencies because the frequency gain was small and we didn’t have quite enough time for that.

We found no compatibility issues between the new card and mainboards. The ATI Radeon HD 4850 successfully started up on our PCI Express 1.0a mainboards as well as on a modern Intel X38 based mainboard with support of PCI Express 2.0.