i am planning to buy a hard drive(wd caviar blue 500 which is 6.0 gbps) but i dont know that can it work smoothly with my GIGABYTE S SERIES G31M-ES2C rev1.1(supports 3.0gbps) Motherboard?
Yes the HDD will run smooth on that MB, it has 4 SATA 3G/B ports to run SATA devices. No worries. Buy the HDD. You could go upto 2TB HDD's without problem.