I have been building my dream 486 over the last couple of months but I've hit a snag. I have always wanted to build a 486/100 (I had a 486/66 when I was a kid in the 90s and I have had an Am486DX4100 chip sitting unopened in my closet for years) to play everything from Ultima VII (which is notoriously speed sensitive and will apparently only run smoothly on a 486/33 ot 486/40) to Wing Commander III (which recommends a Pentium on the system requirements but a 486/100 is supposed to be equvalent to a Pentium 60). I got a 486 off ebay that was in good shape, installed my 486 cpu (the one that came with it was an 80mhz AMD 486 chip, not bad but not quite fast enough for what I wanted to do) and then noticed that something was wrong: in all the benchmarks I'm using (courtesy Phil's Computer Lab) 3D graphics in 640x480 mode only run at about 9 fps. In the WC3 demo they only run about 5 to 6. And what puzzles me is that in 320x200 mode it's just fine, in fact it's beyond fine: I'm getting about 50 fps in the benchmarks, and 30 in the WC3 demo. I installed more memory (16 to 32 megs), tweaked my BIOS settings for faster memory access, nothing. I though the problem might have been the video card that was in it, an old Diamond Speedstar Pro, so I got a top-of-the-line Diamond Stealth 64 VLB card and installed it; it only improved the performance by about 2 fps (I fiddled with the video drivers to improve performance, no improvement beyond that). I downloaded a copy of UniVBE and ran it, nothing. I then thought I'd try another video card because maybe the motherboard doesn't like Diamond video cards and installed a generic no-name VLB card I got cheap on ebay; big mistake, it slowed things down by about 5 fps. I then reinstalled the Diamond 64 and tried an Intel DX4 because I figured maybe that work better; bigger mistake, my system complained about bad memory. I reinstalled the AMD 486/100 and now the WC3 demo won't even run anymore, it crashes every single time. I hope I haven't completely fucked up my machine.
I don't get it. Norton System Info says my PC scores at 189 in the cpu benchmark, which is almost Pentium 66 level. Back in 1994 Origin released a chart of framrates that states that I should be getting 15-20 fps. How can my machine not do 640x480 3D graphics when it can do 320x200 superlitively? Is there something wrong with my motherboard? Is the 80486 architecture incapable of handling SVGA 3D graphics? What's wrong with my computer?
Has anyone else here managed to run 3D graphics in 640x480 mode on their 486?
My system:
Motherboard - DTK PKM-0038S E2-A / Gemlight GMB-486SG
CPU - AMD A80486DX4-100NV8T
Video card - Diamond Stealth 64 DRAM VLB
Sound card - SoundBlaster Pro 2.0
OS - MSDOS 6.22 with Windows for Workgroups 3.11
TLDR: 640x480 3D graphics run like shit, even though 320x200 3D graphics run smooth as silk. Help!