you can buy blank IO shields on ebay for only a few pounds, and then you just need to cut a keyboard hole in it in the correct place 😀

https://www.ebay.co.uk/itm/2PCS-I-O-shield-no … 5.c100005.m1851

As for the power and turbo switches, couldnt you replace the original power microswitch with a latching switch? Or some sort of relay arrangement where the ATX switch triggers a relay which turns on the supply.

For turbo, careful enlargement of a standard hole in the rear of the chassis for a toggle switch would work.

My solution for the power switch is to just use an ATX power supply with a power switch.

Eventually I plan to work out a better solution, along with making turbo switches.

I snatched a 3.5 to 5.25 inch drive bay on ebay with a cutout for USB. I removed the USB ports and will dremel away some bits and pieces and then a standard rocker switch will fit in there. This will be my power button. Also it fits my GoTek nicely, which will soon be modded with an OLED display... 😀

I did not connect the Turbo button. Did not have need for it yet. Reset and HDD LED are connected, though.

Edit: I also bought a few blank ATX IO shields and use a big sink head on a stationary drill to slowly drill a hole for the DIN keyboard socket. Worked like a charm. I can order more and make more, but it won't be cheap. I think they are 8 EUR from mindfactory, and it takes me a bit of time, plus shipping...

Yeah, I went the same route of using the ATX power button for a turbo switch (just replace the momentary switch with a self-locking one inside the button and you're done) and turning the PC on and off with the PSU power switch on the rear. There is also this thing if your model doesn't include the switch:

BTW, mine is not a turbo switch per se (since on my 430VX board it is enabled via a hotkey), but rather a FSB+Multiplier combo: 2 wires for shorting the FSB modifier pins (only 1 state is required to choose between 50 and 66, since with no pins shorted the board just defaults to 66 Mhz) and 3 wires toggle between 1.5 and 2 multiplier on the pin grid behind the CPU heatsink. It does make a difference in some games.

Trying to use an AT PSU in an ATX case could be tricky because many of them only have small power switches so there's no room to replace them with the larger version you'd need. If it were me I'd either sell the AT PSUs or keep them until an AT case comes along, and use an ATX supply in the ATX case. If you want to run an AT motherboard, I've had good success with an ATX PSU to AT motherboard adapter and a latching version of whatever power switch is in the ATX case. If it's a chunky one it's likely to be one like this, or if it's a small one, chances are it'll be more like this 8mm one.

Your BIOS probably has hotkeys for the turbo button. Alt + Ctrl + Keypad plus/minus were common. Otherwise there are many different types of buttons you can get on eBay. Perhaps a nice orange square illuminated one would do nicely for a turbo button? If you don't want to modify the case you could drill the hole for it onto one of the drive bay covers since you'll no doubt have spares of those after installing a floppy or CD drive.

I installed an IBM 5160 XT motherboard in an early 2000s ATX tower case. It's using an ATX PSU with an adapter and I replaced the front power button with a spare I had from an old wrecked AT desktop case, so it switches on and off from the front normally. No Turbo switch on this obviously.

Note: These pictures are a little out of date, they were taken whilst I was still set up with a VGA card. I've since replaced the VGA card with a CGA card, so that isn't pictured here.

Case before it was cleaned:

The Power Button change, original on the left donor on the right.

Case after cleaning:

Inside:

Temporary I/O shield bodge, with a piece of blue card:

Literally the only issue I have with this setup, which isn't really an issue as such - the Reset button on the front of the case is redundant and the Power LED is not connected to anything either.

Interesting I/O shield solution. I might have to steal that idea.

Here's an old link to my solution involving replacing the momentary switches with latching ones:
Re: Wading slowly into the 486 waters
Basically, the power switch continues to turn the system off and on, the reset switch becomes the turbo switch.