There might be a way. Get
Sisoft Sandra, install it, run it, and double-click the Mainboard Information icon. If Sandra can communicate properly with your motherboard, it should be able to tell you what the memory ID's itself as. It'll be under the category "Memory Module(s)"; you might have to scroll a little, and it could give several settings according to the CAS latency setting. My PC2100 memory says CL2.5 up to 133MHz, CL2 up to 100.