It could be both, it may be neither. If you ordered your memory from Crucial after using the Memory Advisor or the System Scanner, then the memory you recieved should be compatible. However, the higher you push the amount the greater strain you apply to the memory controller. So, even if all your memory is compatible and your system is in perfect shape, you may find issues when installing that much memory. So, you may have to perform some minor checks and adjustments. Crucial would therefore be correct in saying that memory is not the issue. However, what they are lacking in explanation is that the amount may be too much. And Apple may be correct in saying that the pc is fine. And what they are lacking in explanation is that the system will be fine so long as you don't push or exceed their standard specifications. Neither is wrong in telling you that no fault lies with them. Since you are the person making the change that causes problems, you need to understand their perceptions of liability.
Test each kit individually using MemTest86+. If neither kit fails, then test each pair of slots. If no slots fail, then your memory controller will just need some extra luvin' to get it to run the memory amount you want. The two methods of stabilizing a controller are through the memory voltage and through the FSB voltage. Try bumping up those voltages slightly, if you can, starting with memory voltage first. Good luck with your upgrade!! And let us know your results. Mac's are especially difficult PCs to tweak.
