Update on this:
Apollboy's Advanced/ML system is now running a Pentium MMX 200, 128 MB EDO DRAM, 4 MB Riva (Velocity 128), 40 GB HDD, USB card, and Win98SE installed. Now using circa 2000/2001 (forget which) beige desktop case I gave him.
I think he's considering adding an ethernet card too.
The Pentium is overvolted at 3.3V, but still runs pretty cool. (that "generic" heatsink he's using also seems to be solid copper 😉)
Some of this was already mentioned here: P55C in a Marl (Advanced/ML) board?
On another note, would anyone happen to know whether the Advanced/ML ever supported the caching beyond 64 MB (with extended tag RAM), or are all stuck at 64 MB? I know the HX chipset can support 512 MB cached, but only with the "optional" wider tag RAM.
If models with both configurations exist, we'll have to take a look at the tag RAM on the board, I guess.
If it's stuck with 64 MB, I'm wondering whether it's worth keeping 128 MB in there. It's primarily a gaming box, so he's not doing much multitasking, and I don't think many/any of the games are memory-hungry enough to need more than 64 MB total (even under 98SE), so the system would probably benefit from using 64 MB of fully cacheable RAM.