Slow HD performance

Question

I have a Samsung SP2504C H.D which is performing way under its rated settings!!under HD Tune benchmark, it scored the following results:Transfer Rate (min) 1.6Mb/secTransfer Rate (max) 3.9Mb/secTransfer Rate (ave) 3.9Mb/secAccess Time 14.5msBurst Rate 4.0Mb/secSciSoft sandra advises that the drive is using UDMA mode 5 but is capable of UDMA mode 7.The mainboard is gigabyte 965P-DS3P withcore2duo 6420 microprocessor2 gB Kingston dual channel 667 ramInno3D Geforce 8600GTThe Bios is Award.Looking forward to your replyDoug Taylor