1. Depends on the CPU. If you want to go >33MHz the CPU needs to be able to handle that. 0 WS is the best for VLB performance - if stable.
2. If the CPU can handle higher speeds, it would be faster if stable. 40MHz or 50MHz would be proportionally faster if you can maintain 0 WS. If not, you need to benchmark in whatever games/applications are important to you to see if the higher speeds with WS turn out faster than lower speeds without the WS.
3. In terms of VLB: yes. If it goes wrong, communications on the bus break down, but nothing is harmed. In terms of CPU, it could damage it due to (localized) overheating. If overclocking, be sure to ensure adequate cooling. We're talking 486 here, so even an Am5x86 with 4x multiplier doesn't need more than a big heatsink without a fan or a small one with a fan, in both cases with a fresh layer of thermal compound, to be more than well enough cooled.

Yep, go ahead!

By increasing FSB, you increase the speed of not just VLB, but also speed to your RAM and cache on board. The whole system benefits. If you have a choice of high-speed+waitstates vs low-speed+no-waitstates, all else being equal, choose the high speed.
But beware - even when the system seems to work decently, then suddenly you may find that data on your harddrive gets corrupted or something weird like that. It may mean that your IO controller is not capable of that speed. Then the story is same - if you can add waitstates on that controller specifically, prefer that over lowering the FSB.

Good luck!
(I'm running Am5x86 @ 3x50 and love it)

Thanks guys, that clarifies a lot already. I'm still not clear on the configuration of my motherboard, though.

Looking at the documentation, I can set the VL-Bus Clock and Wait State only in 2 combinations:
0 WS, <= 33MHz --or-- 1 WS, > 33MHz
By setting 2 jumpers for WS and VLB Clock to either 1&2 on both, or 2&3 on both. Different combo's are not listed in the manual. I mean, I could physically set "0 WS" and "> 33MHz", but the manual doesn't list this as a valid option.

Then I also have a setting named VESA Clock Delay, which is either Delayed or Non-Delayed. In my case, it is set to Delay (the default).

1. There's no word about 40MHz or 50MHz. I assume "> 33" picks a speed automatically?
2. By going ">33", I need to also introduce the 1 wait state, is that logical? Why not >33 and 0 ws?
3. What is this VESA Clock Delay?

Btw: My processor is a 486DX2, 66MHz. It has a heatsink + fan.

Thanks again!

"33 or less" or "more than 33" seems to be another wait-state jumper on many boards, and for best performance, if the cards/board allow, is to keep it at "33 or less". You can try all the combinations and see what works best/fastest/etc.

Erwin_Br wrote on 2023-12-08, 16:51:

Thanks guys, that clarifies a lot already. I'm still not clear on the configuration of my motherboard, though. […]
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Thanks guys, that clarifies a lot already. I'm still not clear on the configuration of my motherboard, though.

Looking at the documentation, I can set the VL-Bus Clock and Wait State only in 2 combinations:
0 WS, <= 33MHz --or-- 1 WS, > 33MHz
By setting 2 jumpers for WS and VLB Clock to either 1&2 on both, or 2&3 on both. Different combo's are not listed in the manual. I mean, I could physically set "0 WS" and "> 33MHz", but the manual doesn't list this as a valid option.

I was looking at VLB I/O card specs the other day and looks like the clock speed thing is separate from wait state, and indicates expected access times for the bus.

The reason that the manual only states two combined options is that it was considered that 0WS >33MHz was not supported/potentially unstable, so that combination was not given. Nothing stopping you trying though.

Then I also have a setting named VESA Clock Delay, which is either Delayed or Non-Delayed. In my case, it is set to Delay (the default).

1. There's no word about 40MHz or 50MHz. I assume "> 33" picks a speed automatically?

The difference between 40 and 50 is negligible, so no separate settings needed.

2. By going ">33", I need to also introduce the 1 wait state, is that logical? Why not >33 and 0 ws?

Because 0WS over 33MHz was considered potentially unstable.

[...]

Btw: My processor is a 486DX2, 66MHz. It has a heatsink + fan.

In that case you are probably going to be CPU limited, as it was a rare DX2-66 that would run at 80MHz let alone 100MHz. Unless you already know this is a very overclockable CPU, you need to look for another CPU before pushing VLB.

It wouldn’t hurt to quickly try if it boots with 40 MHz bus, my Cyrix DX/2 66 had no problem running at 80 MHz. It may also depend on your memory and cache chips, because as was said they will also run faster. Cheap RAM and cache chips may be too slow for more than 33 MHz.