Power Consumption

It is important to know the power consumption of the card you overclock, so we checked out how much power a Radeon HD 3870 overclocked to a GPU frequency of 1GHz needed. We performed our measurements on a special testbed configured like follows:

• AMD Athlon 64 FX-55 CPU (2.6GHz)
• EPoX EP9-NPA+ SLI mainboard (Nvidia nForce4 SLI)
• 1GB PC3200 (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 was created by the first SM3.0/HDR test from 3DMark06 running in a loop at 1600x1200 with 4x FSAA and 16x AF. The Peak 2D mode was emulated by the 2D Transparent Windows test from PCMark05. Here are the results:

Click to enlarge

PowerPlay technology is disabled at extreme overclocking and the core frequency is not varied depending on operation mode. This explains the high numbers in the 2D and Peak 2D modes. The most interesting number is the one referring to the 3D mode: the overclocked card consumed 10W more than the ATI Radeon HD 3870 X2 and the load on both 12V power lines was considerably higher than the allowable limit of 75W. This is the tradeoff of extreme overclocking with GPU volt-modding.

And we doubt the overclocked Radeon HD 3870 is going to be comparable to the ATI Radeon HD 3870 X2 in terms of performance. Increasing the clock rate is a dead-end, actually. The future belongs to multi-core solutions, homogeneous or heterogeneous.