First post, by MisterRed
Hello! I'm new here, hope I'm posting this in the right place...
I have recently come into possession of an old 486-class machine, with a Full YES SIS 486G motherboard, Revision E. I've been restoring it to working order (IDE to SD Adapter, new CD-ROM drive, replacement 3.5" Floppy, etc), and more recently I installed an AMD 486DX4-100 CPU (the later model with 16k L1 Cache). Turns out, my board didn't have a 3.3v regulator on it, so I soldered in an LT1085CT regulator into the vias labeled "Q6" on the board, and it seems to work good. On my Windows 95 SD, everything works normal, no odd behavior after several days of being powered on. But on my DOS 6.22/Win 3.1 card, if I leave it idle, it lets out 3 quick consecutive beeps and blanks the screen. It never did that on the AMD 486DX2-66 chip it came with, and it won't do that if I'm actively using the computer. And again, this doesn't happen on Windows 95. Even on a standard spinning platter hard drive and a fresh install after I upgraded the CPU, it still does this. I can physically touch the edge of the CPU (underneath the heat sink and fan) and comfortably hold it there, so I know it's not overheating.
Any ideas?
-Red