It sounds to me like you might not know what you are talking about. Are you having lag in game, or are loading times taking too long?
If your problems are fps related then it's not your HDD that is the problem, but most likely either your GPU or CPU under performing.
Check with GPUZ and CPUZ if your components are running at the correct clocks and frequencies and that you are not overheating.
Loading times are acceptable.
What I mean is that during gameplay I encounter FPS dropdowns and I see the harddisk working (being orange). The most funny thing is that the same thing was in BLOOD (1997).