kaczor47 wrote:I realize that the memory might not work under CL 2.5 timing, but I was under the impression that the system would adjust and slow things down to CL 3.0, especially when only the 1GB CL3.0 module is installed?
That's something I'm still not sure that all Thinkpads will do (automatically adjust the memory timing). My guess is that most systems are locked into a specific CL (CAS latency) timing and only checks the module's SPD (serial presence detect) information to see if it is capable of running at that timing. If anyone can confirm or refute this point, please let me know.
The SPD information can be programmed so that it lets the motherboard know which timings that module supports.
Generally, if the module is tested and guaranteed to operate at CL2.5, then the bit for CL3 and possibly CL3.5 can also be set. However, if the module is only guaranteed for CL3 operation, the CL2.5 bit should NOT be set. If the motherboard does not read and adjust the memory timings to match the capability of the module(s), then you
may be operating out of spec. Also note: these CL options are at the rated clock speed of the module and does not take into account the use of a different clock rate.
Doing the math for the two different modules (PC2700-333Mhz CL2.5 and PC3200-400Mhz CL3), the actual access times are identical; 7.5ns. Crazyfrog is correct; the PC3200 CL3 should be able to operate at the PC2700 CL2.5 timings. However, if the system insists on using the CL2.5 setting and it checks to see what the module supports, you may have a problem with the 1GB CL3 module.
Of course, you still could have a module with defective memory or some shorted pins and that's what's causing your problem. If you are not getting any kind of beep or error number code, then I'd carefully look at the edge of the SODIMM to see if there are two adjacent traces shorted together.
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