combination DIMMs and SIMMs

[bcris]

I have an AMD K6-2D 266 with mobo S7AX and 32mb sdram pc100. I have an extra dimm slot and two simm slot (72 pins) can I fill all of them with the appropriate memory. Thanks

[charmler]

You can only do that if you can find 5volt dimms. Dimms run at 3.3v and simms at 5v. Placing both runs the whole lot at 5v.

[Nighthawk]

No, you can only run your ram at 1 voltage. SIMMs are 5v, most DIMMs are 3.3v.



you CAN find 5v dimms, but the only motherboards that are keyed to even be able to plug them in are 440FX boards (late Pentium Pro / early Pentium II motherboards)


I HIGHLY recommend not trying it, since you could fry the DIMMs, possibly the SIMMs and motherboard.

[Peter M]

Close, guys, but not accurate.

There are two voltage levels involved: _Supply_ voltage and _signal_ voltage.

While supply voltages may very well be separate and mixed, 3.3V for the DIMMs and 5V for the SIMMs, the signals run to all memory banks and have one single level. Late EDO SIMMs run on 5V supply but use 3V signalling, while earlier stuff runs 5V signalling which will fry your 3.3V DIMM's signal line driver circuitry over time.

So far for the theory ... mixing EDO/FPM and SDRAM technology on the same bus doesn't work very well, in terms of stability, anyway.

regards, Peter