First post, by jasa1063
- Rank
- Oldbie
I was looking into building a Cyrix 5x86 system, but then decided on a Cyrix MediaGX system since this has a Cyrix 5x86 core. I thought this would be a much more interesting build. The biggest obstacle is finding a motherboard. I saw a video on this topic on the CPU Galaxy YouTube channel and he had a link to a seller on eBay. I ordered a motherboard, CPU and accessories. Here are the system specs:
ECS P5GX-M motherboard
Geode GXm-266P CPU @2.9v overclocked to 300MHz (Same as a MediaGX just sold by National Semiconductor after buying Cyrix)
256MB (2x128MB) PC100 SDRAM
3Com Etherlink III network card
TopView ET6000 4MB video card
8GB CompactFlash with a CF to IDE adapter
1.44MB 3.5" floppy drive
16x DVD
Windows 98 SE with Unofficial Service Pack 3
I opted not to use the onboard video as this made overclocking easier and tighter memory timings. I did end up using the onboard SB16 audio. The next issue to resolve was finding a way to tweak the MediaGX register settings. Thanks to this post by feipoa, I was able figure out how to use CTCHIP34 to tweak the MediaGX CPU including enabling Branch Prediciton. I already posted some results in that thread.
Re: Register settings for various CPUs
I have CTCHIP34 in my AUTOEXEC.BAT with the following parameters:
CTCHIP34 cx586 /20:=7
CTCHIP34 cx586 /0e8:=0f8
I have no stability issues except for trying to run DOS Quake at resolutions at 640x480 and above with the tweaks applied. The system just reboots. I got around that problem by using UNIVBE 6.7. There seems to be some issue with the VESA BIOS in the ET6000 card that does not work with the tweaks, but does with UNIVBE. I have no issues in Windows 98 SE and WinQuake runs just fine. Here the results of some DOS benchmarks.
No tweaks applied:
3DBench 1.0c - 156.6 FPS
Chris's 3D Benchmark - 320x200 - 124.3 FPS
Chris's 3D Benchmark - 640x480 - 35.7 FPS
PC Player - 320x200 - 48.7 FPS
PC Player - 640x480 - 19.1 FPS
Doom - Max Details - 86.54 FPS
Quake - 320x200 - 35.2 FPS
Quake - 640x480 - 13.7 FPS
Norton SI 8.0 = 793.9
Topbench 40a - 686
SpeedSys 4.78 CPU Performance Index - 151.09
Tweaks applied:
3DBench 1.0c - 162.3 FPS
Chris's 3D Benchmark - 320x200 - 128.9 FPS
Chris's 3D Benchmark - 640x480 - 35.7 FPS
PC Player - 320x200 - 50.2 FPS
PC Player - 640x480 - 19.7 FPS
Doom - Max Details - 89.02 FPS
Quake - 320x200 - 39.8 FPS
Quake - 640x480 - 15.6 FPS
Norton SI 8.0 - 1020.6
Topbench 40a - 690
SpeedSys 4.78 CPU Peformance Index - 179.82
Overall this has been a fun build. It's basically like having a 486 system on steroids:)