Low GPU memory bandwidth?
 

I recently bought XFX GeForce GT 240 512MB DDR5 and bench-marked it using programs I have: SiSoftware Sandra and m3fe.com fillratetest 1.13.
Both of these tools reported that internal memory bandwidth of my GPU is around 26 GB/s which is about half it should be, 54,4 GB/s. Bandwidth efficiency is below 50%.
Now, I know these larger values are probably theoretical but such results place this GPU significantly below 9600GT DDR3 performance. And this is not the case with all other benchmarks I tried, and it's a bit strange to me that DDR 3 GPU (2 x 950 MHz) can outperform DDR 5 GPU (2 x 1700 MHZ) by 40%, according to Sandra.
Motherboard is Asus P5K Premium with ICH9R and PCI-E 1.1 bus and CPU is Core 2 E8200. Bios is Auto (not overclocked). GPU seems to be running 1700 MHz memory clock during benchmarks (GPU-Z). nvidia 197.45 drivers.

Does anyone know if 26 GB/s (less than 50% efficiency) is indeed low result for this GPU? Do I need to change something in Bios or does it depends on my motherboards PCI-E bus not being v2.0?

Re: Low GPU memory bandwidth?
 

Don't get too hung up on theoretical numbers, the gt240 is on par with a 9600gt in game benchmarks.

Re: Low GPU memory bandwidth?
 

Am trying not to pay too much attention to this.
I figured maybe there is something configured in my system that prevents the GPU to operate at optimum performance.