I have some experience on some Soyo socket 7 boards, which use the same combination of memory sockets (4 simm + 1 dimm). According to the manual, in order to be able to use the dimm socket, you have to fill the first of the two simm banks. And based on what I've tried, I could only get it to recognise 32mb dimms. I'm not sure if that limit is because of the chipset or the board manufactuer. I think those boards I had used the same chipset. So try to fill the first two simm sockets and then install the dimm to see if it works.

Yeah, I considered that too...but this mobo says RAM in DIMM slots in addition to SDRAM is a no-no because of the 5v for the DIMM and 3.3v for the SDRAM. Basically says it will work, for the short term, but the SDRAM will eventually go bye-bye.

Well, I think those boards were made back in a time when most people used simms. On my original pentium PC in 1997(soyo VX board) I had 8MB in simms, and after a couple of years I bought a 32MB SDRAM dimm, and it worked as it should, upgrading the total memory to 40MB. But now that I have several VX boards available to "play", I find it very hard to get them to work on dimms. As opposed to some other TX based boards, that work perfectly using SDRAMs on any combination....

Yeah, I've got 32MB in EDO DIMM's, however, sure would be nice to use the SDRAM if I could. Something I'll have to ponder.

There's no such thing as "EDO SDRAM" that I know of. It must be either "EDO DRAM" or "SDRAM", I think.

Your Aopen AP5VM motherboard seems to be based on Intel 430VX chipset. Some years ago I used a QDI Explorer II, another 430VX motherboard, as my main Socket 7 retro system. It also had 4x SIMM and 1x DIMM slots, which I populated with either 4x 16MB EDO DRAM modules, or a very large and unusual 64 MB PC66 SDRAM module I had. I could only find a single picture of another module resembling that one:

http://www.memosoft.hr/images/LGS%20GM72V1642 … MX4%20SDRAM.jpg

I can't remember whether I managed to get other SDRAM modules working on that motherboard, but that weird PC66 module worked for sure. I also have a 64 MB 168 pin EDO DRAM module that I have never used, but should also work on those motherboards, at least in theory. These ones may be easier to find than the oversized PC66 modules, I guess.

Hrm...I stand corrected, there is a jumper setting on the mainboard that specifies EDO or SDRAM. I've got some weird looking modules like that, but they are IBM 256MB units. I'm sure they won't work in there (double sided, >16 chip count). I wish some of those e-Bay sellers would post real photos of the item instead of those generic stock photos.