Intel's specs say that the 2670QM's memory controller supports 16GB of memory, but they add the qualifier that it is dependent on memory type. Am I correct in assuming that 16 is the highest possible maximum, and not the guaranteed maximum? What happens if I install more than 16? I'm seeing reports of people installing 48GB on consumer desktop i7 setups, which are specced at 24GB, and having them work, so I'm somewhat confused.
The 2670QM supports up to 16GB of memory running at up to DDR3 1333 according to the Intel specifications sheet.
Those i7 computers with 48GB actually support 48GB. That is the maximum they can have but they do support it. Some of the motherboards compatible with that particular chipset (X58 in case you were wondering) are not capable of more than 24GB because they were made before there was reason to support more than 24GB.
If a motherboard was reported to only support 24GB yet works with 48GB then the manufacture probably just didn't test more than 24GB so didn't know if more would work.
Many X58 motherboards support 48GB and that is why some people have 48GB on them although 48GB is very excessive for pretty much anything not server related.
I have spent most of my day and part of yesterday so far looking for an explanation to that. I'm not an expert on memory and don't know what the limiting factors are for knowing the maximum capacity of memory a system can hold but my guess would be that the i7-965 wasn't tested by Intel to find out if it supported 8GB modules because they probably didn't exist (or at least exist for desktop computers) when the CPU was released.
Might be like how pretty much all CPUs can run RAM well beyond their rated memory frequency. The i7-965 extreme says it only supports up to 1066MHz DDR3 but many people have gotten much faster frequencies than that.
However, I did learn that the same 8GB Patriot memory module used in that review is going for $77.99 (free shipping) and with the mail in rebate it only costs $47.99, making it affordable to have 8GB modules right now.