You say you had 2 sticks of 4GB and 2 slots have failed
so why would you buy 4 sticks of 2GB or do you have that the wrong way round?
What type of ram did you buy?
How do you know 2 slots do not work.
Try one new stick only in each ram slot to test if it boots.
Your computer takes
- DDR3 SDRAM PC3-10600 (1333MHz) non ECC
- A DIMM must occupy the black DIMM0 socket. NOTE: Populate the DIMM sockets in the following load order: DIMM1, DIMM3, DIMM2, then DIMM4.
From the Manual for Small form factor - should be the same for all models.
DIMMs The memory sockets on the system board can be populated with up to four industry-standard DIMMs. These memory sockets are populated with at least one preinstalled DIMM. To achieve the maximum memory support, you can populate the system board with up to 16-GB of memory. DDR3-SDRAM DIMMs For proper system operation, the DDR3-SDRAM DIMMs must be: ● industry-standard 240-pin ● unbuffered non-ECC PC3-8500 DDR3-1066 MHz-compliant or PC3-10600 DDR3-1333 MHzcompliant ● unbuffered ECC PC3-10600 DDR3-1333 MHz-compliant (Z200 SFF only) ● 1.5 volt DDR3-SDRAM DIMMs The DDR3-SDRAM DIMMs must also: ● support CAS latency 7 DDR3 1066 MHz (7-7-7 timing) and CAS latency 9 DDR3 1333 MHz (9-9-9 timing) ● contain the mandatory JEDEC SPD information In addition, the computer supports: ● single-sided and double-sided DIMMs ● DIMMs constructed with x8 and x16 DDR devices; DIMMs constructed with x4 SDRAM are not supported NOTE: The 8100 SFF supports 512Mbit, 1Gbit, and 2Gbit non-ECC memory technologies. The Z200 SFF supports 512Mbit, 1Gbit, and 2Gbit ECC and non-ECC memory technologies. NOTE: The system will not operate properly if you install unsupported DIMMs.