So, dual cpus, but not so fast that they overheat and run the fans all the time, etc. - I think there were some problems with dual ross 200s ?
You might want to read
The Rough Guide to MBus Modules
, and in particular the
SPARCstation-20 page in the Systems section
for notes on heat. Aparently the Ross 200s are cooler than some other configurations (such as the Ross 150s and the Sun SM81 modules).
Also note that the SS20 can handle two MBus modules, and each module can have one or two CPUs. So you can put in two dual Ross 200MHz modules for quad CPUs total if you really want to max it out.
TGX+ graphics ?.
If you can find the VSIMM (either 4MB or 8MB), you might like SX graphics instead. But that will reduce the amount of system RAM you can have somewhat. (Although max on the SS20 is 512MB, which is an awful lot for such an old machine. So a reduction might not be too bad a thing.) But the VSIMMs are hard to find and pricey IME. The old
Sun Frame Buffer FAQ
can tell you more about the differences between TGX and SX than I could.