Your options are in part dependent on your motherboard, and apart from one potatocam pic we don't know much about it (looks like SiS 530 chipset)

What you can do in any event at motherboard level:
- reduce multiplier from 5x to 2.5x.
- reduce FSB from 100MHz to 66MHz or possibly 50MHz or lower.
(that's assuming you're running it at 5x100MHz now; if you're on 6x75MHz the same principle remains, just more impact from multiplier).
- disable L2 cache.
- use the integrated graphics in the SiS 530, eating half your memory bandwidth.

But give us more info and we may be able to give you more options.

In theory it should be possible to change the switches in the motherboard in a clever way. (Making a switch of some kind.) But I have no idea if this is 'safe'. I was thinking about doing this but instead I bought an overpriced k6+ from Spain.

Joakim wrote on 2021-08-10, 10:32:

In theory it should be possible to change the switches in the motherboard in a clever way. (Making a switch of some kind.) But I have no idea if this is 'safe'. I was thinking about doing this but instead I bought an overpriced k6+ from Spain.

Perfectly safe if you switch them when the system is off. As for when it's running - check datasheets on the PLL, they frequently tell you which can be switched in operation and which should not. But in case of doubt, power off first.

dionb wrote on 2021-08-10, 09:34:

Your options are in part dependent on your motherboard, and apart from one potatocam pic we don't know much about it (looks like […]
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Your options are in part dependent on your motherboard, and apart from one potatocam pic we don't know much about it (looks like SiS 530 chipset)

What you can do in any event at motherboard level:
- reduce multiplier from 5x to 2.5x.
- reduce FSB from 100MHz to 66MHz or possibly 50MHz or lower.
(that's assuming you're running it at 5x100MHz now; if you're on 6x75MHz the same principle remains, just more impact from multiplier).
- disable L2 cache.
- use the integrated graphics in the SiS 530, eating half your memory bandwidth.

But give us more info and we may be able to give you more options.

Joakim wrote on 2021-08-10, 10:32:

In theory it should be possible to change the switches in the motherboard in a clever way. (Making a switch of some kind.) But I have no idea if this is 'safe'. I was thinking about doing this but instead I bought an overpriced k6+ from Spain.

Thanks for the responses guys!

I was hoping that a Vogons member may have already blazed the software-slowdowns trail for the K6-2/500 non-plus specifically, and journaled it's optimal options for cross-era gaming while avoiding the inconvenience of hardware fiddling each time. Shame it's not a K-6/2+, because then SETMUL offers (virtually) allll the options, at full software convenience, as philscomputerlab and others chronicled in detail a long time ago.

However, your responses have made me think laterally, in the sense that I could bring the (for example) FSB baseline down, which would then make software de-hancements have a proportionally greater effect.

You may have software options for FSB as well, depending on the PLL on that board and what is supported. SoftFSB and CPUFSB are a thing after all, and maybe multiplier control may be done in BIOS instead of jumpers.

Once again, give us more info and you may get more options.

dionb wrote on 2021-08-10, 13:47:

You may have software options for FSB as well, depending on the PLL on that board and what is supported. SoftFSB and CPUFSB are a thing after all, and maybe multiplier control may be done in BIOS instead of jumpers.

Once again, give us more info and you may get more options.

This is the board - an Asus P5-99VM, based on "SiS 530 AGPset" chipset :
https://www.manualslib.com/manual/444796/Asus … ?page=12#manual

I'll check the BIOS for speed options - I hadn't considered utilising BIOS options, but depending on keystrokes involved each time, it might be a tolerable degree of inconvenience. (I don't mean that in the ungrateful sense, but rather that: I'll only bother using a machine to span eras, if doing so falls below a fairly-low inconvenience threshold)

OK, Asus P5-99VM is tough luck when it comes to software settings, as despite it being a very late So7 board, there is no 'auto' option for FSB, multiplier or voltage.

You *could* use an Arduino with a relay board to hook up to all the relevant jumpers, connect the Arduino to a USB port and then use homebrew software to switch it, but that would be quite a project on its own. Now that I come to think of it, it's one I would like to do myself someday. But that doesn't help you now. For now, hardware switches are the only simple option to drop FSB and/or multiplier.

A single tri-polar switch on FS3 would let you switch between 66MHz and 100MHz. Multiplier would be more complicated to halve from 5x to 2.5x, but a single on/off switch on BF2 2-3 would switch between 5x and 3x.

dionb wrote on 2021-08-10, 14:02:

OK, Asus P5-99VM is tough luck when it comes to software settings, as despite it being a very late So7 board, there is no 'auto' option for FSB, multiplier or voltage.

You *could* use an Arduino with a relay board to hook up to all the relevant jumpers, connect the Arduino to a USB port and then use homebrew software to switch it, but that would be quite a project on its own. Now that I come to think of it, it's one I would like to do myself someday. But that doesn't help you now. For now, hardware switches are the only simple option to drop FSB and/or multiplier.

A single tri-polar switch on FS3 would let you switch between 66MHz and 100MHz. Multiplier would be more complicated to halve from 5x to 2.5x, but a single on/off switch on BF2 2-3 would switch between 5x and 3x.

Hmm, well I do have Arduinos and relays handy, but whether I'm into dedicating that degree of resources to it right now is ... questionable for me too! 😀 But perhaps, perhaps (...). You've planted an interesting seed. Great idea!

Yeah I think most of us have an issue with too little time.. I had the same exact idea with an Arduino, it's really quite simple but probably a hassle to set it up for permanent use.. don't want any wires getting loose when you move the case etc...

It occurred to me that even a simple case mod with hardware switches could do a very basic job of externalising jumper changes. It's a way to get 90% result with 5% effort, anyhow.

And who doesn't love flicking old toggle switches???

(as was already told to me as-per-below!, but in my defense it was 2am here when I read it....)

dionb wrote on 2021-08-10, 14:02:

A single tri-polar switch on FS3 would let you switch between 66MHz and 100MHz. Multiplier would be more complicated to halve from 5x to 2.5x, but a single on/off switch on BF2 2-3 would switch between 5x and 3x.

I dunno if any major modding needs to be done even, those side vents look like they'd take small toggle switches with the screw mounting... can't think of right term at moment.

BitWrangler wrote on 2021-08-11, 03:16:

I dunno if any major modding needs to be done even, those side vents look like they'd take small toggle switches with the screw mounting... can't think of right term at moment.

True that. Plus there's my tryhard early-00's fanbus build sitting in the drive bay, and which isn't currently being used for anything.

Yah, it's pretty clean in pics though, wasn't sure if it was case original or not to suggest swiss cheesing it.

dionb wrote on 2021-08-10, 14:02:

A single tri-polar switch on FS3 would let you switch between 66MHz and 100MHz. Multiplier would be more complicated to halve from 5x to 2.5x, but a single on/off switch on BF2 2-3 would switch between 5x and 3x.

I've now set this up, making use of the two formerly-redundant switches on the front panel. Previously, using only L1 cache disablement, the slowest speed achievable was roughly equivalent to a 100Mhz 486.

This new setup allows speeds of 200 - 300 - 333 - 500 Mhz, and L1 cache can be software-disabled at each speed.

Arbitrary Benchmark
SpeedSys v4.78
[L1 cache disabled] :
23 - 25 - 34 - 37
[L1 cache enabled] :
229 - 382 - 343 - 572
For reference, a 486DX2-66 would score around 25 I believe.

Therefore, I now have a range starting around a 60Mhz 486 and up. A significant improvement. Given that the switches are double pole, I should really have gone the extra mile and switched the 2.5 multi instead of the lazy 3.0x - which would have given us a DX2-50-ish equiv. - but, as is often the case, the thought only belatedly occurred to me when I was already balfully into the job.

Nice!

So you have four settings with the two buttons? Not bad! (Even two settings would be alright.)

Maybe try some speed sensitive games, like for instance One Must Fall and Indiana Jones the Fate of Atlantis and see if they run or if you should go even further.

Joakim wrote on 2021-08-13, 05:36:

Nice!

So you have four settings with the two buttons? Not bad! (Even two settings would be alright.)

Maybe try some speed sensitive games, like for instance One Must Fall and Indiana Jones the Fate of Atlantis and see if they run or if you should go even further.

Yes!, and furthermore, I lasted about 0.5 seconds after my last post before not-actual-OCD took over and decreed that I would indeed be making the alteration enabling 2.5x rather than 3.0x.

So now, the two switches (which are old DPDT switches bought once-upon-a-time from now-defunct retailer Dick Smith a long long time ago, but I digress, yes even with the editorial power to delete and-thus-prevent said digressing from ever occurring, deep_breath_in) are Left-to-Right: Multiplier (2.5x, 5.0x) and FSB (66Mhz, 100Mhz).

This gives the possible settings: 166Mhz, 250Mhz, 333Mhz, 500Mhz. That's quite a nice spread, though to be honest only the fastest and slowest settings are going to be relevant to us the majority of the time : in this case being the default fast 500Mhz, and the switched 166Mhz combined with the SETMUL -L1D cache disablement.

I will indeed go and check out some speed sensitive games like the ones you suggest, and see where things stand now.

I can relate to the ocd. In fact, I have a partition called OCD on my Compaq Armada containing the cds for the operating systems.

The thing about OCD is that it isn't in alphabetical order or else it'd be Compulsive Disorder Obsessive, which... would imply a person who was obsessed with compulsive disorders such as OCD.... hmm, kind of like I'm being right now. <backs away from self slowly>

So after testing quite a few games which I'd vaguely consider to be speed sensitive - old Sierra stuff, Doh, Ironman 4x4, Fate, OMF, etc - it was all fine, perfect, using the 166Mhz setting and L1 cache software-disabled. It's slower than I thought actually - loaded up Doom and it was not pleased... slideshow at lowest screen size and low detail. The machine has quite a capable range now! Awesome.

It's great when a plan together comes.....

Well done.