Please confirm that you do have 4 memory slots, and if so, they look like they should work because they match the requirements in your hardware manual as follows:
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 4 GB of memory configured in a high-
performing dual channel mode.
For proper system operation, the DDR2-SDRAM DIMMs must be:
● industry-standard 240-pin
● unbuffered PC2-5300 667 MHz-compliant
● 1.8 volt DDR2-SDRAM DIMMs
The DDR2-SDRAM DIMMs must also:
● support CAS latency 4 and 5 for DDR2/667 MHz
● contain the mandatory JEDEC SPD information
In addition, the computer supports:
● 256Mbit, 512Mbit, and 1Gbit non-ECC memory technologies
● single-sided and double-sided DIMMs
● DIMMs constructed with x8 and x16 DDR devices; DIMMs constructed with x4 SDRAM are not