New RAM is: CML16GX3M4A1600C9B 4x4gb, 1600 MHz, 1.5V.
I don't know why the computer doesn't accept the RAM, (won't start, just starts than instantly turns off)
From my notes:
Intel X79 Express Chipset (Intel BD82X79 PCH)
DD3 Non-ECC Quad Channel supporting overclocked and XMP Memory
4x 240-Pin DDR3 SDRAM Slots for use with the following configurations:
•8Gb (2x4 Gb DIMMS)
•16Gb (2x8 Gb DIMMS)
•24Gb (2x8 Gb + 2x4Gb DIMMS)
•32Gb (4x8 Gb DIMMS)
Personally, I think new-memory 4x4gb-dimms should down-clock and work, but only if it's DDR3. However, I'm sure there are more compatible DIMMs out there. DDR3-1333 PC3-10600 is most compatible.
You could re-install the old working memory and take screen-shots of CPUz's Memory & SPD screens (and then match them closer).