I picked up a nice Packard Bell Legend 245 over the weekend, and it works great apart from one issue so far: when dragging windows around the screen (Win 3.1), the screen gets corrupted with weird snow-like artifacting (see below).
This only happens if I run Windows in 256-color mode. At 16 colors it seems totally fine. The corruption doesn't appear until you drag a window, save for the odd pixel that gets corrupted when rendering text, and it doesn't happen with every drag (but close to it). The snow remains static, and will travel along with the window if I drag it again, potentially worsening each time.
According to MSD, the video BIOS is "LSI Logic Corp. BIOS Code, Version 10.05.03H". There's a single VRAM chip soldered to the board, labeled "NEC 424170-80L", and I can't find any information about it (such as size). I get the same results whether I pick the Super VGA 640x480 256 colors driver, or the Video 7 640x480 256 colors one.
Does this indicate there's a problem with the VRAM? Or do I just need a different driver?
SOME MORE TEST RESULTS:
I hit the turbo button to slow down the system (probably to around 8 MHz based on how horribly it runs), and the snow artifacts were totally resolved. I then adjusted the jumpers to underclock the CPU from 33 MHz down to 25 MHz. The artifacts were substantially reduced (probably by about 75%) but not gone completely. So whatever is going on, the CPU and main bus speed is definitely a factor. And I would assume the RAMDAC has to read the VRAM twice as fast in 256-color mode vs. 16-color mode.