Someone gave me a GCT-8STB based system which uses the SIS 5577 BGA chipset and the AMIBIOS Version 2.4 I have found a little about this (particularly CyberDad's excellent docs). It has four EDO/FP DRAM SIMM (72 pin slots) and two SDRAM DIMM (168 pin slots).
Granted I may not be using the best memory for this board, but I don't want to buy more!
No matter how I set the jumbers or the CMOS and no matter which slots I put memory chips in, it either polls 32MB or 64MB (even when I'm using one 128MB memory stick). Please don't ask me for every serial number and every software version I'm using. I just want to know, if the specs say upgradable to 256 MB of RAM why can't I seem to get past 64 BM? (yes I've looked at the CMOS). If anyone has the setup options (with screen shots) for this exact bios (51-0825-001437-00101111-071595-SIS5577_001_10_SIS5577_H) it would also be very helpful. I guess I also need to talk to the guy that gave me computer and see if he still has the manuals, or if he knows why the memory won't go over 64MB. There isn't much on the internet about this problem, unless I just don't know exactly how to put the search, to get the exact information that I need. Any replies welcome. (Be nice, I'm new here.)_

There is a voltage jumper for the DIMM slots. Perhaps an issue?

http://users.aol.com/dstevens/gct-8stb.htm

Also BIOS:

http://www.bios-drivers.com/drivers/37/37234.htm

Thanks for replying. There are two voltage jumbers, I've tried them both in 3.3v and both in 5v. Also tried one in 3.3 and one in 5 and the opposite, it had no effect. There may be a bios that will work for $30, I got the computer for free and I keep hoping there may be one for free out there. Actually hoping somone has had the exact same problem and can tell me how they fixed it. But thanks again for replying..

I talked to the guy that gave me the the system and he MAY have the manuals, and will look when he gets a chance. He seemed to think the 64Mg limit on the memory was in the BIOS, but the CMOS doesn't say anything about it. The SIS 5577 is no longer supported by SIS website, Perhaps someone has updated Chipset drivers for the SIS5577?