10:31 PM
well some of that is because i overclock both the cpu and push the memory, but just generally when upping it like that, it gets more pickey. a Bootable USB stick, with the MEMTEST86 on it, and a few certian passes , of test 6.
the long version: memory is pretty much all the same, they havent really sped it up a whole lot in ages. The memory to work at certain FSB (base clock speeds) has Timings data on the chip itslef. This is called SPD (what ever that means) Auto , when the bios is on default, it picks up this set of timing paramters for the memory off the chip.
Every Motherboard is slightly different, and when adding in a lot of sticks, the timeing and the slew cant be perfectally matched to the board itself. That is where the "compatability list" for the motherboards comes in.
That is why, 1/2 the people installing loads of memory , send it back for not working :-) When usually all that is needed, is for the memory to be taken off of SPD (or AUTO) and the timings to be tuned, till it always passes a good hard memory test.
So all these cute numbers we see on the memory 1600 2000 1300, or whatever, are not (as much) how fast the memory itself actually is, but more how the Timings are set , and read by the mother board. notes: there are faster and slower controllers and chips, but that has little to do with Timing the memory to work at the 1300 1600 and 2000 numbers they are selling us.
Once you take the memory off of auto, you see all kinds of cute numbers, with all sorts of fun names , and different boards use sligtly different names. Basically this sets certian "wait states" (my words) for the speed of the memory. CAS RAS REFRESH, and other complicated stuff. that is were we get another set of numbers 7-7-7-21 and 9-9-9-32 or whatever. those are the timings.
If you raise these numbers , you put in more "wait states", and the memory is sure to work. so BEFORE stuffing in a whole new rack of memory. a person can Lower the Divisor (the ratio between the base speed and the memory). And take the memory off of auto, and raise the timing numbers, and the chances of the memory update working in one move will be much higher.