Can't boot with new memory

[David12345]

Motherboard: MSI 790FX-GD70
Memory: DDR3 1333 (PC3 10666) F3-10666CL7D-4GBRH
CPU: AMD Phenom II X4 965

Started with one set (two sticks), and that ran fine (other than not having enough memory!)

I just recently ordered another set (two sticks), using the same part number from Newegg. The sticks seem to be the same model (the labels have been re-arranged a bit since I ordered the first set).

However, if either or both of the new sticks are in the machine, it won’t boot – posts up to D5 and then just stops. This happens even if I remove the first two sticks and put the two new ones in their place.

It would seem that all of the normal issues that could prevent boot with new memory (speed, size, etc) could not be a factor here because these two sticks should be the same as the two that are working fine!

I’m probably just missing something stupid, but I can’t think of what it might be!

Thanks!

[emissary42]

Did you clear the CMOS beforehand? The newer kit might need different secondary timings*, so i would give it a shot.

*The ICs used to build this kit might have changed over the years because of availability. So there is no guarantee, that two of those kits that were bought years apart play well together.

[David12345]

Well, that's disappointing... it won't help to get the new kit working, if that means that the old kit won't work, since I still won't be increasing the total memory. It looks like I need to start completely over with all new memory.