- Jun 25, 2007
Just out of curiosity what possessed you to snub VLB boards? They were the superior option for i486 systems...I may have mentioned this system in a thread about ISA overclocking awhile back, but here is the 486 system I have been using several months now. The particular motherboard I chose (after a lot of research) for my signature ALL ISA 486 build will run DOS/Windows 95 rock solid stable at 13.2MHz ISA and DOS but not Windows stable at 16.5MHz ISA. Hence I settled on IBM PC-DOS 7.0 as it's slightly lighter on resources then DOS 6.22, and I normally run 13.2MHz ISA when I'm gaming on the system (16.5MHz only when benching). Using a modified exe called FastDoom, my system will push 50-60fps in most areas of the original Doom levels and 52.6fps at 13.2MHz ISA and 55.5fps at 16.5MHz ISA in the 3DBench VGA benchmark. I credit the relatively unknown Symphony chipset and the WD90C31A video card for this performance. From my testing I think the WD90C31A (at least my DFI manufactured one) may be faster then the Tseng Labs ET4000AX, which is considered one of the fastest ISA cards. Overclocking the ISA bus definitely wakes up the VGA performance! When I built this system I set out to see if an all ISA 486 could compete with a VLB 486 system, and in my various benchmarks it is quite competitive with VLB systems based on the benchmarks I have seen on the internet. I'm using an Evergreen upgrade CPU which is basically an AMD 5x86 133MHz adapted to an interposer with a voltage regulator on it to allow it to work in older 5 volt only 486 motherboards. Interestingly I also have an Intel DX4 100MHz OverDrive CPU that benches about the same as the AMD at 133MHz using common 486 era benchmark programs. Where the 133MHz helps is in Build engine games - Duke Nukem 3D runs quite smooth at 320x200, on the 100MHz CPU Duke 3D can have some minor stuttering. Another game that benefits from the 133MHz is Chasm: The Rift.
One of these days I'll finish restoring the case the system is in, as it is the build runs fine but I have no front panel installed.
You're leaving performance on the table, but you already know that. Lol
Unrelated, I've ordered an 8800 GT 512MB and a Q6700 for period correctness. In thinking about it, G92 is a much better choice for what I want to do with this system. More to come.