high pitch noise from pc can anyone help?

Could be your hard drive, check that.

Probably from the graphics card. Have the same issue when running Sims 3, the only thing that helps is to manually set the driver to use Vertical Sync or something like that when running that specific game. Check for a solution in that direction maybe.

As they say i would also say HardDrive, but you should be able to identify the sound coming from it, hardly but you should, put your ear close and use that superman ear power :P, and yep if it is the HD it will be dead soon :(

Suppose if it is like the test tone, it could be the HDD as suggested. But, a lot of whistling or higher pitched noises can also come from dust chunks and hair built up in fans and other moving parts. Always worth opening your PC and giving it a careful checking and cleaning.

Maybe coil whine from your PSU.

My guess: it's the GPU

you could try a video benchmark (at your own risk) and see if it's reproduceable

Just the game using more power in my experience. Low requirement games dont ever my computer make that humming noise while games like Nosgath or when I start 8 different games on to get steam cards from them then it makes that same noise.

Coil whine?

I am thinking PSU as well

I say its a hard drive 98%

You don't still have a CRT, do you? Those things were LOUD.