am5x86 p75 vs P24T

RichM499

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I recently finished building my vintage gaming PC. I wanted a machine I could play my really old Windows and MSDOS games with as well as some of the 1996-1999 3D games.

Specs:
AM5x86 p75 133mhz @ 160mhz
1GB HDD using on-board controller (This will be 8GB with Promise Ultra ATA/100 controller soon)
Voodoo 3 3000
32MB 72pin EDO RAM (This will be 64MB soon)
Yamaha OPL3-SAx sound card 100% sound blaster compatible

I decided to purchase a Pentium Overdrive (P24T) 83mhz socket 3 chip to measure the performance compared to the AM5x86 p75 chip, and to my surprise the AMD chip far outperforms the Pentium Overdrive. In QuakeGL I was able to get 13FPS average with the AMD chip, and the Pentium Overdrive only delivered 8FPS. I am convinced I can get the FPS up to around 15FPS with the AMD chip. I was unsuccessful at getting Super Pi 1.5 XS to run on this system, but I will be trying some older benchmarks over the next few days and posting the result screenshots here.

Do you have any ideas for good benchmarks that work in Windows 98 or MSDOS?

So far the games that work and are completely playable on my AMD 486 chip are Forsaken, QuakeGL, GLHexen II, Monster Truck Madness, Space Quest 6, and some other 2d titles. The OpenGL games run very smoothly most of the time, but they slow down to around 8-10 FPS during scenes of heavy action.

Do you have any recommendations for methods for increasing performance?

Edit: Changing the PCI burst write and CPU - PCI write/read settings improved performance slightly. Also, l2 cache WriteThrough seems faster than WriteBack for some reason. This old motherboard doesn't give me DRAM timings or specifics, but changing it from slowest to fastest seemed to make a small difference. I was able to get 14.4FPS in QuakeGL which makes it pretty smooth for the most part. It's very playable, and I was able to get through a few levels without major slowdowns except for the areas with a bunch of enemies in open spaces. Interestingly, there is no performance difference between 320x200 and 512x384 resolutions (i.e. they both scored 14.4 FPS in Timedemo demo2), and 640x480 is only very slightly slower (it's 14.3fps). I did not expect this result. I thought for sure the lower resolution would perform better.
 
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I think you can use up to 3dmark 2000 on that setup.

If you're using 98se there are a lot of unofficial tweaks and updates you should use that greatly helps with OS performance.
 
I'm using regular Windows 98. Do you have any links to the tweaks you're talking about? I have three different AM5x86 p75 chips, so I might try overclocking it to 200mhz by pushing the bus up to 50mhz, but this will also overclock the PCI bus, and I don't know if my PCI cards are going to like that.
 
Here are some pictures of my system. It scored 15 3dmarks and 5 cpu marks in 3dmark99 MAX. I am able to run Turok Dinosaur Hunter, Quake GL, and Tomb Raider 2 at full speed except for when the screen is full of enemies and effects, and that's impressive to me for a 486 machine! I have been unable to get the system to run Super Pi 1.5 XS, but I will try that again when I get my Promise ATA/100 controller card and 8GB hard drive (I will install Windows XP or 98se on it).

My system defaults to 100mhz when I try to push the FSB up to 50mhz for 200mhz CPU, and I am not sure why. It looks like 160mhz is as fast as it will go for me. I tried ADW and BGC chips, and I have a really nice ADZ chip with an exposed VRM and dip switches, but I broke one of the pins, so I will need to fix that before I really play around with it. I am planning to use the ADZ with a Chaintech PCI socket 3 motherboard. I also tried an 83mhz Pentium Overdrive, and my am5x86 @ 160mhz beats it in all tests by a long shot (I was surprised, I thought the Pentium would have a superior FPU and run 3d games faster than the 486 AMD chip, but I was wrong).

Edit: You may notice I have wadded paper holding up the motherboard. I had to find a way to keep it from sagging because I can not screw it directly into the motherboard tray because of the standoff layout of the motherboard, but it works! :D
 

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AT cases are getting hard to come by. The only ones I found on Ebay were around $80-$150, which is overpriced in my opinion since almost nobody is looking for this stuff anymore. I think the Am5x86 is probably the fastest socket 3 chip in the world. It definitely beats Pentium Overdrive 83mhz, but I have not yet tried the Cyrix media chip with special instructions. There is a 133mhz Cyrix chip that may actually perform better than the chip I have now, but it's really rare, and I can't seem to find one.
 
I can get some pretty cool stuff from this shop down the road from me. Probably get an AT setup for pennies. They even have a sealed Pentium Pro but they want a stupid amount of money for it. I just don't have room in my tiny apartment for so much crap and my hardware collection already takes up half of one of my storage buildings :(
 
I was able to get 18.1fps with sound on in QuakeGL 640x480 with the AM5x86 p75 at 160mhz, and 24.2fps with no sound. I started out a few days ago at 14fps, so I am pleased to be making progress. I would test my Pentium Overdrive 83mhz, but the system won't boot with it installed (I think maybe it's busted because I plugged it in wrong, and it will POST.) If I can find some info on an ALI motherboard I have; I will test it more.

The Sound Blaster 5.1 PCI in the picture is surprisingly a 3d decelerator. With it installed; the FPS in games is terrible due to a jerky stutter. I thought Sound Blasters were good hardware acceleration, but I guess since this one is rustic it's backwards now, and that's interesting because the drivers installed fine for it.. More pics later if I can get my Pentium Overdrive running properly.

Edit: Tomb Raider 2 runs at the same FPS in 320x200 as 1600x1200, which is very surprising to me. It's perfectly playable at 1600x1200, and I like that. QuakeGL crashes at any resolution above 640x480 for some reason.
 

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