My screen freeze after a few minutes of youtube or vimeo streaming

Hi,

Please find my question, some background info and my assumptions below. Has anyone experienced this?

Thanks

K

Question;

GPU about to fail, other hardware issue or software issue?

Symptoms with history;

While watching some video on youtube or vimeo, my MBP screen went patchy in places (2x2cm blocks of colour pixels flickering randomly). Turned it OFF normally.

Back ON, the dock icons went translucent. Turned it OFF normally.

Cooling for 10min. Reset PRAM. Restarted. All good.

Then, again watching some other streamed video, my MBP froze. NO RESPONSE except for moving the mouse. No clicking, no nothing. FORCE SHUTDOWN.

Freezing has happened again today, for the 3rd time in 2 days.

Other Info

1) GPU has been repaired once in the past.

2) When freezing, GPU heatsink reached around 80 deg C according to iStats Menu.

3) Right fan has been making grinding noises (mostly at start up) for the past week although appears to spin normally (i.e. 2000 rpm standard, iStats Menu reading)

4) In between freezings, I have watched half a DVD with no issues whatsoever.

Assumptions

Streaming is GPU intensive, more so than playing a DVD, therefore makes the GPU heat up. Bad heatsink cooling could cause the MBP to freeze??