wdc5000bpkt-00pk4t0 suppose to be 500GB but turn out to be 73.95

bought the hard drive and when i instqll it it shows its only 73.95GB,…am stunned,…its suppose to be 500GB?,.whats wrong??

Check on disk management to see if the remaining space is not partitioned, if not, your motherboard might not support a 500GB hard drive, check if you have any BIOS updates available.