King's quest - Use the thunderboard setting instead of sound blaster, solves most speech related crashes
Dreamweb - Very little info but if it doesn't ask for IRQ/DMA try setting sound card to IRQ7 DMA1 as some games are hard coded to look for these values. It may also have a speed sensitive sound driver that stops working with faster computers.

Yes, Thunderbird will solve speech locking up your PC in King's Quest, but Thunderbird sounds awfully muffled. At that point, you lose the benefit of playing the game on real metal and may as well run it on SCUMMVM in Windows.

Use nothing faster than a 486/DX-33 for that era of Sierra games.

Thank you both for your replies and suggestions! I tried Jan Knipperts' Opti 929 drivers, but still no sound at all in Dreamweb. I swapped the 929 for the 924 I have, which is supposed to be extremely similar. I used Jan Knipperts' 924 driver since it is a tweaked and updated driver, and Dreamweb is now working. It is strange that the 929 is not working at all with Dreamweb. I may try to reproduce the issue in 86box. I wanted the 929 in my 486 as it is closer to period correct than the 924, but all well...

The KQ5 lockups were happening between two very different systems, so maybe it is speed related. I can moslo the 486 down to 33Mhz, and retest. I know it isn't cd speed related since I copied the files from the CD and altered the resource.cfg file. Whatever Opti card I had back in 1993 was perfect with any game I played at the time (King's Quest VI came with it in a Reveal Multimedia Upgrade Kit,) and I never had any issues in any game as long as I didn't have any IRQ conflicts, so it is weird to be experiencing these issues now. Granted, I did not own Dreamweb or KQ5 at the time...

Well, running KQ5 with moslo /50 seems to work. However, maybe I wasn't experiencing as many lockups as I previously thought. I am using a CF/IDE adapter with an 8GB CF card, and a HDD Clicker. In the games I have tested, thus far, the HDD is accessed A LOT. Whenever I click anything in the games tested, there is a pause while the HDD thrashes, and then the game action commences - usually when there is some sort of complex animation, or a line of speech. Well, this is happening A LOT in KQ5. I decided to sit and wait and I could keep playing whereas I previously thought that I was experiencing some manner of lockup. I mean, there were definitely some non-HDD-thrashing lockups happening, but this game is nearly unplayable with this HDD thrashing. It interrupts speech, which means possibly losing critical information. I am unsure what to do to solve this issue. Right now, I have RAM limited to 8mb in my config.sys. I will remove that to enable the full 16mb. Other than that, I have no idea. I am using a Zida 4dps Tomato board, and all settings related to HDD are set to AUTO. Maybe the adapter is faulty, or something wrong with the CF card, my RAM stick, or even the IDE cable. I have very few old school IDE cables that lack that one pin being blocked off, so I will have to hunt some down.

Scythifuge wrote on 2025-12-12, 06:39:

Well, running KQ5 with moslo /50 seems to work. However, maybe I wasn't experiencing as many lockups as I previously thought. I am using a CF/IDE adapter with an 8GB CF card, and a HDD Clicker. In the games I have tested, thus far, the HDD is accessed A LOT. Whenever I click anything in the games tested, there is a pause while the HDD thrashes, and then the game action commences - usually when there is some sort of complex animation, or a line of speech. Well, this is happening A LOT in KQ5. I decided to sit and wait and I could keep playing whereas I previously thought that I was experiencing some manner of lockup. I mean, there were definitely some non-HDD-thrashing lockups happening, but this game is nearly unplayable with this HDD thrashing. It interrupts speech, which means possibly losing critical information.

Does the HDD thrashing happen even when you run the game directly from the CD?

ALL forms of slowing down a CPU are not equivalent to the actual MHZ value of the system.

For example, you can take a VIA C3 and clock it down to 150Mhz, at which point I believe it is even slower than a 486, but you'll still get lock-ups in Sierra games, because the engine still does not like the 150Mhz.

It is very specific in that way, so if you must run those Sierra games in a non-virtualized environment, I repeat, run them on period-correct hardware. Otherwise use ScummVM. ScummVM has a lot of bug fixes as well that it incorporates into the games.

Personally, I prefer to run them on period correct hardware -- but it is an investment.

I played all Sierra games originally on a Pentium 1 166 MHz, and I don't think any game locked up. There were speed errors and sometimes audio conflicts, obviously not ideal, but nothing that stopped me playing any game I think.

NeoG_ wrote on 2025-12-12, 09:17:

Scythifuge wrote on 2025-12-12, 06:39:

Well, running KQ5 with moslo /50 seems to work. However, maybe I wasn't experiencing as many lockups as I previously thought. I am using a CF/IDE adapter with an 8GB CF card, and a HDD Clicker. In the games I have tested, thus far, the HDD is accessed A LOT. Whenever I click anything in the games tested, there is a pause while the HDD thrashes, and then the game action commences - usually when there is some sort of complex animation, or a line of speech. Well, this is happening A LOT in KQ5. I decided to sit and wait and I could keep playing whereas I previously thought that I was experiencing some manner of lockup. I mean, there were definitely some non-HDD-thrashing lockups happening, but this game is nearly unplayable with this HDD thrashing. It interrupts speech, which means possibly losing critical information.

Does the HDD thrashing happen even when you run the game directly from the CD?

I will test this, soon. I reinstalled everything on a different CF card and spent a lot of time getting the Opti 924 card working properly in DOS and Windows 3.1.

mockingbird wrote on 2025-12-13, 23:11:

ALL forms of slowing down a CPU are not equivalent to the actual MHZ value of the system. […]
Show full quote

ALL forms of slowing down a CPU are not equivalent to the actual MHZ value of the system.

For example, you can take a VIA C3 and clock it down to 150Mhz, at which point I believe it is even slower than a 486, but you'll still get lock-ups in Sierra games, because the engine still does not like the 150Mhz.

It is very specific in that way, so if you must run those Sierra games in a non-virtualized environment, I repeat, run them on period-correct hardware. Otherwise use ScummVM. ScummVM has a lot of bug fixes as well that it incorporates into the games.

Personally, I prefer to run them on period correct hardware -- but it is an investment.

Unfortunately, the slowest PC I have is the 486DX2/66. I do remember KQ6 playing fine on my very first PC, a 486SX/33 - with an Opti card (1993.). Another option, if I get an HDMI-to-VGA adapter that can support MS-DOS resolutions at 70Hz, is to use 86box with my CRT VGA monitor. In this way, I can create specialized VMs for various games and apps, such as a 386 for these speed sensitive games.

Scythifuge wrote on 2025-12-15, 03:52:

Unfortunately, the slowest PC I have is the 486DX2/66. I do remember KQ6 playing fine on my very first PC, a 486SX/33 - with an Opti card (1993.). Another option, if I get an HDMI-to-VGA adapter that can support MS-DOS resolutions at 70Hz, is to use 86box with my CRT VGA monitor. In this way, I can create specialized VMs for various games and apps, such as a 386 for these speed sensitive games.

There's not much you would have to do to replace the DX2/66 with a DX/33. No jumpers to replace -- just swap the chip.

mockingbird wrote on 2025-12-15, 13:44:

Scythifuge wrote on 2025-12-15, 03:52:

Unfortunately, the slowest PC I have is the 486DX2/66. I do remember KQ6 playing fine on my very first PC, a 486SX/33 - with an Opti card (1993.). Another option, if I get an HDMI-to-VGA adapter that can support MS-DOS resolutions at 70Hz, is to use 86box with my CRT VGA monitor. In this way, I can create specialized VMs for various games and apps, such as a 386 for these speed sensitive games.

There's not much you would have to do to replace the DX2/66 with a DX/33. No jumpers to replace -- just swap the chip.

Many people speak about setmul as something that works better than most slow down methods. I don't know if it is any better with Sierra games due to what you were saying. However, I did try it with my 486DX2/66, and it claims to have knocked the Mhz down to 15Mhx, and it does feel slower in game, but issues persist. I may look into grabbing a 33Mhz CPU.

I read that the Windows version of King's Quest V MPC is general midi compatible. I tested that out with an SC-55 soundfont on my MP32L connected to a PicoGUS. While annoyingly not able to play in fullscreen and the pixel-icons looking like Windows icons, the game seemed to play and sound good. Instruments sounded good, I could hear the flowing water outside of the village, and I did what I could to reproduce the lock ups and stutters, and I couldn't do so. This may be the way I have to play the game, for now. I do have a CT1600 Sound Blaster Pro2 on the way, and I will run tests with that on a separate CF card with fresh installs of everything.

Scythifuge wrote on 2025-12-15, 21:08:

Many people speak about setmul as something that works better than most slow down methods. I don't know if it is any better with Sierra games due to what you were saying. However, I did try it with my 486DX2/66, and it claims to have knocked the Mhz down to 15Mhx, and it does feel slower in game, but issues persist. I may look into grabbing a 33Mhz CPU.

Setmul won't change the multiplier for a 486 DX2/66, that's hardwired by motherboard jumpers. I'm not sure what it did on your system.

It will work with a Cyrix 5x86 CPU though, you can truly slow down a 5x86 to 33Mhz and you effectively have a way to switch between a 'slow Pentium' and a 486DX/33 with the command line. But I think you need a relatively 'new' 486 motherboard for it.

mockingbird wrote on Yesterday, 05:09:

Scythifuge wrote on 2025-12-15, 21:08:

Many people speak about setmul as something that works better than most slow down methods. I don't know if it is any better with Sierra games due to what you were saying. However, I did try it with my 486DX2/66, and it claims to have knocked the Mhz down to 15Mhx, and it does feel slower in game, but issues persist. I may look into grabbing a 33Mhz CPU.

Setmul won't change the multiplier for a 486 DX2/66, that's hardwired by motherboard jumpers. I'm not sure what it did on your system.

It will work with a Cyrix 5x86 CPU though, you can truly slow down a 5x86 to 33Mhz and you effectively have a way to switch between a 'slow Pentium' and a 486DX/33 with the command line. But I think you need a relatively 'new' 486 motherboard for it.

When I use setmul L1D, it says that my cpu is not supported, but changes the Mhz. If I run games after that, they are very slow, usually most noticeable in cutscenes. For exampled, I loaded up Ultima - The Savage Empire, and the opening panning screen is very slow and jerky, but the actual gameplay seems okay. Setmul L1E brings the Mhz back up to 66, and the opening cutscene is very fast. I should test it out with Wing Commander. However, since it doesn't help with KQ5, and makes games tested way too slow in parts, I will probably never use it on this system. It helps me a lot on my Pentium 166 though. I beat Wing Commander 1 and 2 with setmul on that system.

Another thing I tried was CD Be Quiet, which when used claims to work (I tried everything from 1x to 4x speed.) However, when loading up a game that tests drive speed, it shows that it isn't working. Dune's test reports a much faster than 4x drive, and Sierra games that test drive speed crash and then requires a reboot in order to install the game. So, another thing I need to try is to swap out my 16x DVD writer until I find a drive that works with cdbq. I will also try KQ5 on the P166 with setmul, though it is driving me nuts that a solution for this 486DX2/66 is eluding me.

The documentation for setmul says it can modify the cache enable/disable register on 486 CPUs so that's what it is doing. It's still running at 66Mhz, but with significantly reduced efficiency. Benchmark tests like Landmark will show an "equivalent" speed of 15Mhz AT but it doesn't measure the actual frequency, it runs a mathematical test and compares how long it takes to run versus an 80286 AT system. Needless to say that a 15Mhz equivalent 80286 is not fast enough to run many VGA era games, except for the earlier adventure games. Wing Commander would run too slow.

With CDBQ, many drives will reset the drive speed every time a disc is inserted. So if you are setting the speed to 4x and then putting a disc in the drive, it will have reset back to full speed before you run the test. Many people find CDBQ not particularly useful for that reason. I found when using it on an IDE DVD writer the drive would eventually lock up when using a slower speed as well.