So I have a somewhat dated CPU (i5-750) and motherboard (GA-P55-UD2 rev 1.0) that are spec'd up to 16gb RAM, but that was when 8gb RAM sticks did not exist. I have read one thread where two users with a i5-750 CPU report that they are able to use 32gb RAM. There are also numerous threads online where other people with the same chipset but different CPU`s used 32gb RAM while specs said max 16gb.
Now I wanted to upgrade my system to 32gb RAM (for photo and video editing), bought the sticks and put them in. Three sticks of 8gb (24gb total) work in any combination of the four sticks that I bought, so all sticks work and they can all work together. Adding the fourth to make 32gb total makes it not work. BIOS recognizes the 32GB but windows wont boot beyond the loading screen where the little dots go around in circles.
Since the BIOS recognizes the RAM and there is not particular reason for windows not to accept a certain size of RAM, I think the bottleneck is somewhere inbetween: the motherboard/chipset or the CPU (memory controller is integrated). Since other people have reported being able to use a i5-750 and the p55 chipset with 32gb of RAM I figured I might be able to as well. I have not found other people with the same motherboard as me that have reported to run 32gb RAM, so it may just be impossible.
In case four large RAM sticks was just asking too much juice I lowered the frequency of the RAM, increased VRAM to 1.65 (1.5 previously) and QPI voltage to 1.15 (1.05 previously), but that didnt change anything. My question now is are there any other tweaks that I might try to get the same results other people did?