I managed to get the CT4170 to detect, by setting the FSB back down to 33 mhz from 40 mhz. After that first boot at 33 mhz, it would successfully detect every time, even @ 40 mhz, strange how it would refuse to initialize only for the first time @ 40 mhz.

After that, I installed the card through the "found new hardware" dialog. At the end, I got a window asking me to confirm the resources used, which I left as is (they were the same as in Win 98). But after rebooting, no sounds would play, even tho I could adjust the volume and "play" sounds thru the control panel. Upon shutting down, it would get stuck at a blank teal screen, as if trying to play the shutdown sound indefinitely.

I finally got it working by removing the SB16 device in the Control Panel's Multimedia Properties, rebooting, then adding the "Creative Labs Sound Blaster 1.X, Pro, 16" from Multimedia Properties:

In the configuration popup, I left the default resources:

The second DMA channel is 5, whereas the "found new hardware" install that didn't work had the second DMA as 3 (and wouldn't let me change it).

The only issue from here is the "found new hardware" box every startup that I have to cancel. But that's the least of my worries as the sound is now working... and yes, I repeated all of the above at both 33 mhz and 40 mhz with the same results. Now I still can't get the damn mouse to work on this mobo. It seems the 4DPS uses a non-standard serial header pinout. But I have an ISA serial card on the way, so I'll see if that lets me use a mouse.

When you overclocked the FSB, did you also change the clock divider in the CMOS setup?
At 33 MHz, it should have a divider of 4, but at 40 MHz it should be 5.

By keeping the divider at 4 and with a FSB of 40 MHz, you're running your ISA bus at 10 MHz, which could be the cause of your problems.

jesolo wrote on 2021-01-30, 22:48:

When you overclocked the FSB, did you also change the clock divider in the CMOS setup?
At 33 MHz, it should have a divider of 4, but at 40 MHz it should be 5.

By keeping the divider at 4 and with a FSB of 40 MHz, you're running your ISA bus at 10 MHz, which could be the cause of your problems.

That was my first suspicion, but the ISA clock is set to the default 7.15mhz. I didn't try any other settings because the lowest divider in my BIOS is /4. There's no /5, /6 etc.

Just a followup which will hopefully help anyone else who's struggling to get sound or mouse working on the 4DPS:

The "Creative Labs Sound Blaster 1.X, Pro, 16" driver quit working yesterday. I tried again to install the CT4170 through the "found new hardware" popup, but it still wouldn't play any sounds.

Even though using the latter method wouldn't let me change either of the the two DMA settings at first, I did notice that there were different "basic configuration" settings that I hadn't messed around with before. I chose "basic configuration 0005" instead of "basic configuration 0000" since it only had one DMA setting. I then manually set "Direct Memory Access" to 01 from 00. When I clicked OK and rebooted, the sound was working again!

As for the mouse, I got an ISA serial card off Ebay, and at first the mouse would only work in NT 4 but not 98. In 98, the mouse would be detected (no error, cursor appears) but wouldn't move or click. I disabled the on-board serial ports and jumpered the ISA card to COM1 and COM2, but that didn't help. I then checked the IRQ's of COM1 and COM2 in the device manager (this is tricky to do w/o a mouse, but possible using Alt+letter keyboard shortcuts); they were set to 4 and 3 respectively (and couldn't be changed). I then swapped the jumpers on the ISA card from 3/4 to 4/3; the mouse finally works under both 98 and NT.

These ISA cards are still readily available on Ebay, just search "lava isa serial"

Also this motherboard flat-out refuses to install Windows 2000, locking up at a black screen right before the GUI setup, right after the bootloader. This is the second motherboard I've gotten the past couple months that seems incompatible w/ W2K w/o explanation (the first was a VT586VX(C) socket 7) but I'm honestly not too bothered now that 98 and NT are finally functional.