Memory compatibility: any insight appreciated

[libbyQ]

Although fairly technically literate, it never ceases to swamp me the confusion over how to tell what kind of memory module a PC should take. I thank CPUID, the makers of CPU-Z freeware. I downloaded and ran their informative app. It says that my PC has an available memory slot. Good. It says the existing slot uses type DDR, PC3200 (200 MHz), single channel, and a number of other more obscure specs are also shown. I haven't looked inside the case quite just yet. Can you tell from the stated specs how many connectors/pins my existing module has? Is it 240-pin? Is 240-pin DDR2 SDRAM compatible? Is DDR2 800 (PC2 6400) compatible? (I have some lying around unused.) Why or why not (briefly)? What about those other obscure specs, latency and RAS# and all? ..do those parameters all get ignored in determining compatibility?

I'm delighted to have a tool like CPU-Z. I wish I had some semblance of a handle on using it effectively to figure compatibility of memory modules to PCs. Some electronic modules are backward compatible. Is that true of memory generally? Obviously, add-on memory has to have the exact matching connector strip. What are the very most critical factors besides that? Yo, spoil me rotten.

And I'm also a bit curious, if I put incompatible memory into a slot that fits it perfectly, it WON'T harm my PC, right?? It just won't be detected or used properly, is my belief. If that happens, one could just remove the offending module and revert to previous, without harm. Please confirm.

Many thanks!

[Aaron_8015]

No DDR2 memory will not work in a DDR slot.... DDR is 184 pins (I believe).

Normally it is best to get matching pairs of memory for dual channel and compatability...... Mixed does work as long as the motherboard supports it...
e.g. 1 stick of PC2700 and 1 stick of PC3200 will run together at the slowest sticks speed.

As to your last question.... I don't know... I have never tried it, but due to the different amount of pins I cant imagine it would do it any good.

[libbyQ]

Quote:

Originally Posted by Aaron_8015

As to your last question.... I don't know... I have never tried it, but due to the different amount of pins I cant imagine it would do it any good.

Thanks, your reply is mighty helpful all told!

You misunderstood the last part though. I opined it would do NO HARM to put incompatible memory in a slot that it fits into perfectly, ie with identical connector strip configuration. And the remainder of your sage reply to my post seems to imply that when the connector strip is identical then the memory modules should interchange compatibly, with possible compromise in speed.

[hugorudd]

In general that's right. It should never realistically cause any damage to a piece of memory to plug it in if it fits. The voltages applied at boot time are pretty low, and shouldn't be sustained enough to do any damage.