I changed 2B to 82, and my 770 still sees all the RAM, but only 288 MB is "usable". This could be a good start...Wow, ok. EVEREST reports that DIMM 0 doesn't exist, and DIMM 1 shows 32 MB. DIMM 2 still shows 256 MB. I think that the old DIMM 1 was disabled, and DIMM 0 took its place.
2B is now set to 83, and only 256 MB is "usable". Now, EVEREST only sees one RAM stick, and I'm assuming it's the one that used to be DIMM 2.
2B is now 84, and 288 MB is usable again. Ah HA! Now we're getting somewhere! All 3 DIMMS are available. Everything is just like it is when 2B is set to 80, except now DIMM 2 only has 128 MB of RAM usable. 32 + 128 + 128 = 288.
2B at 85 gives me 256 MB of usable RAM. Now, both 256 MB sticks are being used, but only 128 MB on each. The onboard 32 MB is disabled.
2B at 86 gives me 160 MB of usable RAM. 32 MB onboard is enabled, and one of the two 256 MB sticks is enabled at 128 MB.
Whuh oh, 2B set at 87 gives me only 128 MB of RAM. The onboard 32 is disabled, and one 256 stick is being used at 128.
88 gives 288 again. 32 + 128 + 128.
89 gives 256...128 + 128.
90 gives 416. 32 + 128 + 256.
00 gives 416. I think the only thing that matters is the second part of the number. What does the first part do then?
Tried something with a letter in the second part, and now I have to reset CMOS. I think I'll stop, because it seems 2B won't help enable any more RAM. I'm thinking that there's either another byte that we should be editing, or the chipset just can't handle the extra RAM.