First we tried to overclock our ASUS GeForce GTX 660 DirectCU II OC at its default GPU voltage and found it to have good overclocking potential in terms of GPU frequency and average in terms of memory frequency. Without compromising on stability and image quality we managed to increase the GPU and memory clock rates by 140 and 780 MHz, respectively.
The resulting clock rates were 1160/1225/6788 MHz:
That’s a very good result, especially as the GPU clock rate was boosted to 1255 MHz at peak load while the temperature was still no higher than 62°C.
The peak speed of the DirectCU II fans was only 30 RPM higher than at the default clock rates, reaching 1620 RPM.
We measured the power consumption of our testbed equipped with different graphics cards using a multifunctional Zalman ZM-MFC3 panel which can report how much power a computer (without the monitor) draws from a wall outlet. There were two test modes: 2D (editing documents in Microsoft Word or web surfing) and 3D (three runs of the Metro 2033: The Last Refuge benchmark at 2560x1440 with maximum image quality settings, but without antialiasing).
For comparison purposes hereinafter we also added the results for ASUS GeForce GTX 660 Ti DirectCU II TOP 2 GB, Sapphire Radeon HD 7870 GHz Edition OC 2 GB and HIS 7850 IceQ Turbo X 2 GB. Let’ see what we got:
The configurations with different graphics cards don’t differ much in their power consumption. The system with Sapphire Radeon HD 7870 OC consumes more than the others, up to 408 watts at peak load, which is 30 watts more than required by the system with ASUS GeForce GTX 660 Ti TOP. The overclocked ASUS GeForce GTX 660 consumes about 10 watts more but has the same power consumption as the 660 Ti TOP at the default clock rates. The HIS Radeon HD 7850 IceQ Turbo X system is the most economical one.
We can only add that a 500-watt PSU is going to be enough for any of these configurations. Each of them needs no more than 220 watts of power in 2D applications.