Lothar

As I posted in another thread here, I have a new system that has at least one bad RAM DIMM, and the vendor has sent me several replacement sticks for troubleshooting purposes. No matter how I swap and reposition the DIMMs, the bad memory error messages that I'm getting are failing to help me narrow it down to just one DIMM (it's not worth going into the details here, but suffice it to say that tech support is as stumped as I am), and it's possible that I have *two* bad DIMMs. At the very least, I have narrowed it down to two of the original DIMMs that are definitely working fine, and am debating whether it's worth the effort to troubleshoot it any further, given that I have free replacements that I can use.

The problem is that the original DIMMs have a CAS latency of 555, and the replacements are a slower 666. These are 1GB DDR2 ECC SDRAM modules (x4 for a total of 4GB).

My question is, what is the best way to mix and match these DIMMS in my 4 memory slots? Here are my options:

1) Continue the troubleshooting and try to narrow down the bad memory to a single DIMM, and then use three 555 DIMMs plus one 666 DIMM.

2) Don't bother with any further troubleshooting, assume that I have two bad DIMMs, and use two 555 DIMMs plus two 666 DIMMs

3) Replace all of the DIMMs with the slower 666 DIMMs so that they are all the same spec.

Which of the above three options will give me the best performance (if there would even be any noticeable difference), and in what order should I arrange the DIMMs in the four slots for either options 1 or 2?

According to my system's manual, DIMMs should be installed first into DIMMs 1 and 2, then any additional DIMMs into 3 and 4, so that is how the slots are paired.

Lothar