Chosen Solution
As above really, started to freeze a week ago, hard boot only way to restart, watching onboard movies/videos or streaming seems to cause the freeze. Also since starting to find causes on the web, fast scrolling also causes the freeze. From my PC days I’m thinking ram problem, diagnostics say they are fine but is there a way of testing them. Hoping not the logic board Any advice would be appreciated
Givens the systems age I’m suspecting your GPU card needs some service. Over time the thermal paste and thermal pads loose there effectiveness so when the GPU or the video RAM overheat the video image can suffer breakdown as you’ve described. Here’s a IFIXIT vid on someone who had a bad card. Here’s we don’t need to bake the board as your card just needs a TIM refresh. Take note this person used thermal paste on the RAM chips. Apple used a special gapping paste which I don’t recommend! And applying standard paste on top is not really that effective. Proper thermal pads are superior in their effective heat transmission. iMac Intel 27" EMC 2374, AMD Radeon HD 4850 Video Card Removal & Repair Do make sure you follow proper ESD protection practices. The bubble wrap is not something I would use as it can be statically charged (some are ESD safe)
