I have recently done a second memory upgrade on this Lombard and put in a new HD. Now, with either the new or the old memory and HD, I get apparently random freezes, crashes, etc. The machine seems to work normally when starting from cold but after a while (I assume when it starts to heat up) the freezes start.
The advice I have been given from several sources (but not here!) was to make certain that the processor board was properly seated on the mother board. I have done this a number of times with no improvement.
I notice that the contact between the processor and the heat sink is mediated by a white compound which may have lost its effectiveness thanks to the heat sink having been pulled off a number of times. It is normally recommended to replace such thermal compounds every time you reinstall the heatsink but the Apple Service Documentation makes no mention of this.
So - my questions :is this a known issue, do the symptoms accord with this being the problem, is it a good idea to replace this compound, if so what is it and where can I get some (I'm in Europe)?
I know that thermal compounds are available but reading an AMD report suggests that there are a number of different sorts and, rather than try and second guess the Apple designers, I'd rather get the "right stuff". Or perhaps, given that the machine is now 4-5 years old, maybe better stuff?