CL5 memory unstable in Dell Optiplex

[cocjh1]

Hi,

I've a Dell Optiplex 755 uSFF with following memory requirements:

Type 667-MHz or 800-MHz DDR2 SDRAM
Memory connectors 2
Memory modules supported 512 MB, 1 GB, or 2 GB non-ECC
Minimum memory dual-channel: 1 GB;
single-channel: 512 MB
Maximum memory 4 GB
BIOS address F0000h

Upon replacing the stock 2x1GB sticks of Samsung M378T286QZS-CF7 CL6 with 2x2GB sticks of Crucial CM2X2048-6400C5C CL5 memory the system (66% of time) will not pass POST. The occasions the system does pass POST the resident O/S boots and runs ok for hours..

Ok, so I know now I've purchased memory with the wrong CAS Latency (CL5 instead of CL6) but why does the system sometimes work with CL5 fitted?

Ta,
Chris

 

[Mattyjw]

Try it with one stick of ram at a time it could be that ones failing and halting post. the latencies shouldn't make any difference. Try giving the ram more volts although if the bios is on auto it should work. The first thing is try one stick of ram at a time.