Power Consumption, Noise, Temperature and Overclockability
The GeForce 9800 GTX uses a different power circuit and works at higher frequencies than the GeForce 8800 GTS 512MB. That’s why we performed our standard procedure of measuring the new card’s power draw on a special testbed configured as follows:
- AMD Athlon 64 FX-55 CPU (2.6GHz)
- EPoX EP9-NPA+ SLI mainboard (Nvidia nForce4 SLI)
- PC3200 memory (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
The 3D load is created by running the first SM3.0/HDR test from 3DMark06 in a loop at 1600x1200 with 4x FSAA and 16x AF. The Peak 2D load is emulated by means of the 2D Transparent Windows test from PCMark05. We got these numbers:
As might have been expected, the new card is not much different from the GeForce 8800 GTS 512MB in terms of power consumption. The peak power draw is not higher than 110W, so our prediction was quite correct. The distribution of load shows there is no need for two external power connectors: each of them has a load of about 32W in 3D mode, the combined load being barely above 60W. If these connectors were loaded more, to offload the PCI Express x16 slot, they could be explained by Nvidia’s desire to put a smaller load on the mainboard which might make sense for SLI and especially for 3-way SLI configurations. But the consumption on the internal +12V line is the biggest, exceeding the consumption of the GeForce 8800 GTS 512MB on the same line. So, the two 6-pin PCI Express 1.0 connectors on board the GeForce 9800 GTX can only be the result of marketing consideration winning over common sense. Pre-overclocked versions of GeForce 9800 GTX, which are sure to appear, are unlikely to have a much higher power draw and won’t need the two connectors, either.
Anyway, the new flagship card from Nvidia doesn’t have a voracious appetite especially if compared with the GeForce 8800 GTX. You don’t need a very advanced PSU for it. Any 400-450W PSU with two graphics card cables will do because the Gainward Bliss 9800 GTX 512MB comes without Molex → 6-pin PCIe adapters.
The cooling system installed on the GeForce 9800 GTX is in fact identical to the cooler of the GeForce 8800 GTS 512MB, and their noise characteristics should be the same. We checked this out 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. Here are the results:
The new card is about as noisy as its predecessor GeForce 8800 GTX. It is almost silent at work – you can only hear it if it is the single source of noise in your system case, which is improbable. The cooling performance is high because the G92 chip generates less heat than the G80 this cooler was designed for. According to RivaTuner, the GPU temperature was 48°C in idle mode and 61°C under load on an open testbed. The numbers will be higher in a closed system case, but the GeForce 9800 GTX is unlikely to overheat anyway.
We were quite lucky with our GeForce 9800 GTX at overclocking. We managed to reach 800/2000MHz for the graphics core and 1300 (2600) MHz for the memory. The card passed a few cycles of 3DMark06 tests at such clock rates, but began to fail after a while. At GPU frequencies of 770/1925MHz the card was stable but there are image artifacts like flickering colored spots in 3DMark06. These were eliminated by reducing the memory frequency to 1250 (2500) MHz. Thus, the final frequencies of the card, according to RivaTuner, were 771/1944MHz for the core and 1252 (2504) MHz for the memory. The GPU temperature was 64°C under load on an open testbed.
The card started up successfully on our PCI Express 1.0a mainboard. Mainboard supporting PCI Express 1.1 and 2.0 should all be compatible with it as well.