Frequent crashes - RAM, GPU, fan, browser?
Hi - I've been experiencing frequent crashes since about a year ago. I've been troubleshooting and trying to solve it since then, in between deadlines. I'm still having the crashes, though, so I need to hear any suggestions on what this might be. I'll try to describe the problem(s) and what I've done as clearly as possible (and, I've been troubleshooting for some time, so I hope you wouldn't find it a problem that my description below is quite long).
When they started happening, the crashes usually seemed to be related to Safari. The whole OS would freeze, then restart itself. So I stopped using Safari and installed Firefox. Using Firefox worked for a while, until I started getting the same crashes again. This was why I started carefully backing up (by cloning and with time machine). By the way, all along, the internal HDD was fine (checked with Disk Utility).
At this point, I was still trying to keep Mac OS X 10.7.5 (because of some softwares that might've not worked well if I had upgraded). But I eventually planned a clean install of Mountain Lion, because I thought perhaps my 10.7.5 was too outdated already.
Before I got to install Mountain Lion, though, a few weeks ago at one critical point (I was finishing up a Keynote doc with lots of images), my laptop froze again. This time, however, it was followed by the 3-beeps, and it didn't restart itself. I gathered (googled) that this was potentially a RAM problem.
So, what I did was, firstly, to clean install Mountain Lion (as I've been planning to do it for some time). This didn't seem to help with the crashing (although it did get rid of clutter in my system, and I now have much more free space in my internal HDD).
Next, I installed Memory Clean v4.8 (FIPLAB) and tried to control my memory usage through it. There seemed to be no connection between my RAM usage and the crashes. Around this time, just after my laptop started to freeze, the screen would be covered in random (interference) lines before the whole system would shut down and go to the 3-beeps. It wouldn't restart itself - I would have to hold the power button down for a while to get the 3-beeps to stop. Then I'd be able to restart it.
What I did after this was opening up my laptop. I opened it following the instructions carefully, e.g. took off the battery cable before fiddling with the RAM sticks. I also cleaned it (it wasn't visibly dirty apart from a ø2mm of whitish powdery stuff between the RAM sticks and the battery cable). Took off both RAMs at first, let it do the 1-beeps for a minute, then put 1 RAM back. When I turned it on, it worked for 2 minutes before it started freezing again, with the random lines on the screen, but no beeps. It also didn't restart by itself. So I restarted it, and managed to run with 1 RAM stick for quite a while, monitoring the usage with Memory Clean. This was the first time I could work for a whole length of time, and I could properly shut it down again when I finish working.
Because I needed the whole 4GB RAM to work, I put the other stick in again. When I did a system profiling ("About This Mac") I saw that the Memory slots and sticks were reported as "OK" (2GB + 2GB) - but this has always been the case, even before I took the RAMs out. So I thought to do a proper test - what I did was the memtest 4.2.2. I booted as a single-user (command-s while starting up), and ran the memtest for a bit more than 6 hours (17 repeats).
Memtest reported there was no problem with the RAMs. Then, for the next 2-3 days it was very peaceful - I could work without crashes, and I would be able to properly shut down at the end of the day.
Just a few hours ago, however, my laptop started freezing again, and restarting itself. There's no beeping anymore, but the crashes now are quite frequent (around 10 times the last 2 hours), and the random/interference lines came out 1 time (out of about 10 crashes).
The only difference between today and the past 2-3 days when I could work very peacefully was that I had the browser on (first it was Firefox, then when it started crashing, Safari) when the system crashes, and I was doing quite extensive work on Facebook.
I've just installed TGPro (trial at this point) and it looks like my laptop's temperature is usually 3-4ºC above the "average" (as TGPro says on its interface).
A friend had a similar problem, went to a technician and was advised that they had to replace the GPU "and a few ICs on the board".
Any suggestions on what I should/could do next?