I have some RAM I have been trying to upgrade this machine with.
I have currently in the machine 2x2GB.
I tried upgrading by switching out the 2x2GB for 4x4GB (which the machine should be capable of running). I performed a PRAM and SMC reset, and the machine would boot, log in and open some apps before then crashing/rebooting, each time with unspecified triggers.
I tried using 4x2GB and the same problems would occur. I have currently switched back to 2x2GB and it seems ok but I am finding it hard to understand what may be causing this problem and if there is a way of resolving it so that I can successfully upgrade?
Edit - it seems like it was bad RAM as 4x2GB seem to be working alright.