Sun,
What brand of video card do you have?
You MAY have to try a different tweaking tool other than Precision tool with it. I have had a couple cards, the Zotac comes to mind, that did not allow the fan to manually adjust and let me put the slider where I wanted to. Had to run on automatic and max was 74 percent.
Let's start there.
micro...
BTW. good job on acquiring the component parts.