I recently tried upgrading the memory on a Dell 7810 Desktop computer. These computers have 8 memory slots. The memory I was trying to install is from Dell Part # SNPH5P71 /8G the ones that are in the computer now are 4 gig stick but they are running at the same speed. I am pretty sure there is two physical processors. Does it matter if I mix different size memory on a computer like this if the memory is running at the same speed?