Is it possible to upgrade the memory to 4MB? Is there any difference between 2 MB and 4MB on board?

It's different between 2 Meg and 4 Meg. Basically, the 4meg can support more graphics resolution. But if you want to upgrade 4 Meg, it would be more stable to use the same EDO RAM on this board.

I have a DSV3325DX card with 4MB RAM, however I cannot get the resolution 1152*864 to display true colors. Can I upgrade the memory to 8MB to solve this problem?

Even the DSV3325DX card maximal size ram is 4MB, it still can't support this resolution.

How do I change IRQ 15? It tells me that it will conflict with the "Secondary IDE Controller".

Exchange the position of the device. It may resolve this problem.

Is the S3 VIRGE/DX card compatible with the LX motherboard?

The S3 Virge-based VGA card is the most popular product for high performance 3D graphics in Pentium (or equivalent) systems. However, the Pentium II and 440LX based motherboard has incompatibility problems with the card. For this reason, many motherboard and VGA card manufacturers have put updated versions into the market. Ask the LX M/B supplier to provide you with the information to solve any problems. The Sales Support Department of DataExpert is willing to verify the compatibility test before your purchase. If your LX M/B supplier was unable to solve the problem, we are able to offer a compatible S3 Virge-based VGA card. By presenting the M/B, pre-testing will be more efficient. Please notify us if there are any problems.