izaacdoyle :
I've built a PC there a year ago and I bought the sapphire radeon r9 270x 4gb but it is only saying it is running at 3.5 GHZ . and I was told it is ment to be at 5.6 GHZ
3.5GHz sounds like a CPU clock speed, not the GPU.
5.6GHz is probably the effective video card memory speed. The GPU core isn't that high, but DDR5 on a GPU has a high multiplier and runs very fast.