My hunch is that either VGA card BIOS is expecting DDC to be working and it is not through the VGA to HDMI adapters that you are using OR the adapters you are using do support DDC but in a way the video card BIOS does not like.

You could try comparing the DDC info you can get from the monitor + adapter versus what you grt from your TV to try to get an idea about what might be happening. Entech in Taiwan used to have some free utilities for that, AFAICR.

Alternatively, you could sacrifice a VGA cable or extension by removing the monitor ID and DDC pins from it. If that cable no longer works even on the TV, it means the VGA card needs DDC to work. If it works on both the TV and with adapter+monitor, then that likely means it does not need DDC, but is not happy with it's getting through DDC from the adapters.

Oh, and welcome to Vogons !

darry wrote on 2025-03-25, 14:56:

My hunch is that either VGA card BIOS is expecting DDC to be working and it is not through the VGA to HDMI adapters that you are using OR the adapters you are using do support DDC but in a way the video card BIOS does not like.

You could try comparing the DDC info you can get from the monitor + adapter versus what you grt from your TV to try to get an idea about what might be happening. Entech in Taiwan used to have some free utilities for that, AFAICR.

Alternatively, you could sacrifice a VGA cable or extension by removing the monitor ID and DDC pins from it. If that cable no longer works even on the TV, it means the VGA card needs DDC to work. If it works on both the TV and with adapter+monitor, then that likely means it does not need DDC, but is not happy with it's getting through DDC from the adapters.

I think I have a spare VGA cable I can cut into, I'll try it.

I have 2 other video cards I can try, I've got a Geforce 4 MX 440 AGP and an ATI AIW 9200se. (I was thinking those cards are too new for a Win98 "period correct" build?)

And thanks for the welcome!

I've had similar behavior with Radeon 9250 over DVI. When i go to full screen command prompt from windows 98, screen goes just blank. I can exit the full screen command prompt and everything continues to work properly.
It's not every 9250, just some of them. Transplanting bios from one (where text full screen works) to another card unfortunately did not succeed. (I suspect bios to be the issue)

As you have completely different card... maybe it's somehow related to drivers instead? A faulty driver installation or something?

GigAHerZ wrote on 2025-03-25, 15:15:

I've had similar behavior with Radeon 9250 over DVI. When i go to full screen command prompt from windows 98, screen goes just blank. I can exit the full screen command prompt and everything continues to work properly.
It's not every 9250, just some of them. Transplanting bios from one (where text full screen works) to another card unfortunately did not succeed. (I suspect bios to be the issue)

As you have completely different card... maybe it's somehow related to drivers instead? A faulty driver installation or something?

I have seen this with DVI/HDMIas well on older Nvidia cards as well.

The way I understand/interpret it, based on the tests it took to get it working, essentially, at least some Nvidia vBIOSes on cards with a TMDS limited to 165MHz (pixel clock) will not display anything in POST/BIOS /DOS on monitors with a native resolution whose timings requires >165MHz of bandwidth.

This is due to mode selection logic in the vBIOS trying to select the monitor native resolution but the TMDS possibly either being incapable of that OR possibly because there is a safeguard in the vBIOS that prevents overclocking the TMDS.

The logic in newer Windows drivers usually handles this more gracefully, so you can get a picture under Windows (not to mention that some drivers allow overclocking the TMDS to beyond 165MHz), but the vBIOS has no fallback or overrides available. The only workaroud I know of is to use a custom EDID with a native resolution that is within the range of DVI limits, which can be done either using a programmable inline EDID emulator OR by reprogramming the monitor's EDID.

Analogue VGA typically should not require DDC, but there might be scenarios where it either is required or where it actually breaks things, as I suspect is the case for OP's setup.

darry wrote on 2025-03-25, 16:32:

I have seen this with DVI/HDMIas well on older Nvidia cards as well. […]
Show full quote

GigAHerZ wrote on 2025-03-25, 15:15:

I've had similar behavior with Radeon 9250 over DVI. When i go to full screen command prompt from windows 98, screen goes just blank. I can exit the full screen command prompt and everything continues to work properly.
It's not every 9250, just some of them. Transplanting bios from one (where text full screen works) to another card unfortunately did not succeed. (I suspect bios to be the issue)

As you have completely different card... maybe it's somehow related to drivers instead? A faulty driver installation or something?

I have seen this with DVI/HDMIas well on older Nvidia cards as well.

The way I understand/interpret it, based on the tests it took to get it working, essentially, at least some Nvidia vBIOSes on cards with a TMDS limited to 165MHz (pixel clock) will not display anything in POST/BIOS /DOS on monitors with a native resolution whose timings requires >165MHz of bandwidth.

This is due to mode selection logic in the vBIOS trying to select the monitor native resolution but the TMDS possibly either being incapable of that OR possibly because there is a safeguard in the vBIOS that prevents overclocking the TMDS.

The logic in newer Windows drivers usually handles this more gracefully, so you can get a picture under Windows (not to mention that some drivers allow overclocking the TMDS to beyond 165MHz), but the vBIOS has no fallback or overrides available. The only workaroud I know of is to use a custom EDID with a native resolution that is within the range of DVI limits, which can be done either using a programmable inline EDID emulator OR by reprogramming the monitor's EDID.

Analogue VGA typically should not require DDC, but there might be scenarios where it either is required or where it actually breaks things, as I suspect is the case for OP's setup.

I did my testing with a 1600x1200 screen that at that resolution supports 60Hz and on some lower resolutions can do 75Hz. So it should comfortably fit under 165MHz, yet i still had this issue...

GigAHerZ wrote on 2025-03-25, 16:46:

darry wrote on 2025-03-25, 16:32:

I have seen this with DVI/HDMIas well on older Nvidia cards as well. […]
Show full quote

GigAHerZ wrote on 2025-03-25, 15:15:

I've had similar behavior with Radeon 9250 over DVI. When i go to full screen command prompt from windows 98, screen goes just blank. I can exit the full screen command prompt and everything continues to work properly.
It's not every 9250, just some of them. Transplanting bios from one (where text full screen works) to another card unfortunately did not succeed. (I suspect bios to be the issue)

As you have completely different card... maybe it's somehow related to drivers instead? A faulty driver installation or something?

I have seen this with DVI/HDMIas well on older Nvidia cards as well.

The way I understand/interpret it, based on the tests it took to get it working, essentially, at least some Nvidia vBIOSes on cards with a TMDS limited to 165MHz (pixel clock) will not display anything in POST/BIOS /DOS on monitors with a native resolution whose timings requires >165MHz of bandwidth.

This is due to mode selection logic in the vBIOS trying to select the monitor native resolution but the TMDS possibly either being incapable of that OR possibly because there is a safeguard in the vBIOS that prevents overclocking the TMDS.

The logic in newer Windows drivers usually handles this more gracefully, so you can get a picture under Windows (not to mention that some drivers allow overclocking the TMDS to beyond 165MHz), but the vBIOS has no fallback or overrides available. The only workaroud I know of is to use a custom EDID with a native resolution that is within the range of DVI limits, which can be done either using a programmable inline EDID emulator OR by reprogramming the monitor's EDID.

Analogue VGA typically should not require DDC, but there might be scenarios where it either is required or where it actually breaks things, as I suspect is the case for OP's setup.

I did my testing with a 1600x1200 screen that at that resolution supports 60Hz and on some lower resolutions can do 75Hz. So it should comfortably fit under 165MHz, yet i still had this issue...

That also depends on the timings for 1600x1200 @60Hz that the monitor EDID exposes. That resolution is at the very limits of DVI and requires timings with a reduced blanking interval. That being said, your issue might be havebeen due to buggy/bad vBIOS logic or a combination of factors. DVI was flaky at times during the early years.

I pulled up the manual for that monitor and there is a page showing supported resolutions and timings, and it didn't list anything below 640x480 for either HDMI or displayport. You'll likely need some kind of scaler device for it to work, or try to find a monitor that still has a VGA port. I use an OSSC with mine since although my monitor does have a VGA input the aspect ratio is all wrong at lower resolutions and the OSSC can correct that, although it's overkill for this application.

darry wrote on 2025-03-25, 16:54:

GigAHerZ wrote on 2025-03-25, 16:46:

darry wrote on 2025-03-25, 16:32:

I have seen this with DVI/HDMIas well on older Nvidia cards as well. […]
Show full quote

I have seen this with DVI/HDMIas well on older Nvidia cards as well.

The way I understand/interpret it, based on the tests it took to get it working, essentially, at least some Nvidia vBIOSes on cards with a TMDS limited to 165MHz (pixel clock) will not display anything in POST/BIOS /DOS on monitors with a native resolution whose timings requires >165MHz of bandwidth.

This is due to mode selection logic in the vBIOS trying to select the monitor native resolution but the TMDS possibly either being incapable of that OR possibly because there is a safeguard in the vBIOS that prevents overclocking the TMDS.

The logic in newer Windows drivers usually handles this more gracefully, so you can get a picture under Windows (not to mention that some drivers allow overclocking the TMDS to beyond 165MHz), but the vBIOS has no fallback or overrides available. The only workaroud I know of is to use a custom EDID with a native resolution that is within the range of DVI limits, which can be done either using a programmable inline EDID emulator OR by reprogramming the monitor's EDID.

Analogue VGA typically should not require DDC, but there might be scenarios where it either is required or where it actually breaks things, as I suspect is the case for OP's setup.

I did my testing with a 1600x1200 screen that at that resolution supports 60Hz and on some lower resolutions can do 75Hz. So it should comfortably fit under 165MHz, yet i still had this issue...

That also depends on the timings for 1600x1200 @60Hz that the monitor EDID exposes. That resolution is at the very limits of DVI and requires timings with a reduced blanking interval. That being said, your issue might be havebeen due to buggy/bad vBIOS logic or a combination of factors. DVI was flaky at times during the early years.

I wonder, if it could be somehow fixed?

The 9250 i have that is properly working, has 166MHz VRAM. The one, that has issues under windows in text mode has 200MHz VRAM. (Both are 128bit, so the "better ones")
I really like those cards.
NVidia 440MX with DVI was way worse - in motherboard BIOS, it had like half a second delay and super slow text draw routines over DVI. You could see how bios redraws symbols! 😁 Over VGA, everything was snappy as it should.
9250, when DVI does work, it works beautifully.

GohanX wrote on 2025-03-25, 17:10:

I pulled up the manual for that monitor and there is a page showing supported resolutions and timings, and it didn't list anything below 640x480 for either HDMI or displayport. You'll likely need some kind of scaler device for it to work, or try to find a monitor that still has a VGA port. I use an OSSC with mine since although my monitor does have a VGA input the aspect ratio is all wrong at lower resolutions and the OSSC can correct that, although it's overkill for this application.

Well that's what the 2nd VGA-HDMI adapter was supposed to do, it output 720P 50/60Hz or 1080P 50/60Hz. Even with that I got nothing on the monitor until Win98 loaded. I'm returning that converter though, it was blurry AF and had ghosting on the desktop for whatever reason...

I'm going to try the other GPUs I have tonight as well, see if they make any difference.

As for the DDC and ID pins, that is just pin 12 on the VGA cable correct? Just snip that off and test it out?

Silver_Pharaoh wrote on 2025-03-25, 18:13:

Well that's what the 2nd VGA-HDMI adapter was supposed to do, it output 720P 50/60Hz or 1080P 50/60Hz. Even with that I got noth […]
Show full quote

GohanX wrote on 2025-03-25, 17:10:

I pulled up the manual for that monitor and there is a page showing supported resolutions and timings, and it didn't list anything below 640x480 for either HDMI or displayport. You'll likely need some kind of scaler device for it to work, or try to find a monitor that still has a VGA port. I use an OSSC with mine since although my monitor does have a VGA input the aspect ratio is all wrong at lower resolutions and the OSSC can correct that, although it's overkill for this application.

Well that's what the 2nd VGA-HDMI adapter was supposed to do, it output 720P 50/60Hz or 1080P 50/60Hz. Even with that I got nothing on the monitor until Win98 loaded. I'm returning that converter though, it was blurry AF and had ghosting on the desktop for whatever reason...

I'm going to try the other GPUs I have tonight as well, see if they make any difference.

As for the DDC and ID pins, that is just pin 12 on the VGA cable correct? Just snip that off and test it out?

There are several ID pins, AFAIU. This is from a quick google search. https://www.keepbestpcba.com/vga-connector-pi … ut-explanation/

EDIT: Other sources indicate pin 12 as being enough. I have never had to do this on a VGA cable, personally, AFAICR.

darry wrote on 2025-03-25, 21:47:

Silver_Pharaoh wrote on 2025-03-25, 18:13:

Well that's what the 2nd VGA-HDMI adapter was supposed to do, it output 720P 50/60Hz or 1080P 50/60Hz. Even with that I got noth […]
Show full quote

GohanX wrote on 2025-03-25, 17:10:

I pulled up the manual for that monitor and there is a page showing supported resolutions and timings, and it didn't list anything below 640x480 for either HDMI or displayport. You'll likely need some kind of scaler device for it to work, or try to find a monitor that still has a VGA port. I use an OSSC with mine since although my monitor does have a VGA input the aspect ratio is all wrong at lower resolutions and the OSSC can correct that, although it's overkill for this application.

Well that's what the 2nd VGA-HDMI adapter was supposed to do, it output 720P 50/60Hz or 1080P 50/60Hz. Even with that I got nothing on the monitor until Win98 loaded. I'm returning that converter though, it was blurry AF and had ghosting on the desktop for whatever reason...

I'm going to try the other GPUs I have tonight as well, see if they make any difference.

As for the DDC and ID pins, that is just pin 12 on the VGA cable correct? Just snip that off and test it out?

There are several ID pins, AFAIU. This is from a quick google search. https://www.keepbestpcba.com/vga-connector-pi … ut-explanation/

EDIT: Other sources indicate pin 12 as being enough. I have never had to do this on a VGA cable, personally, AFAICR.

Alright I chopped pins 11,12 &15 and still no screen during BIOS, but Win98 is still fine.

Sorry, not sure how to edit posts, (all I see is the delete post option?)

So I tried the ATI All In Wonder 9200SE, and the Radeon VE PCI card (which apparently is dead) both had no difference.

So I tried the GeForce 440MX with a DVI to VGA adapter and lo and behold I see the BIOS and full screen DOS works!

The modern monitor reports 1080P as the resolution. Maybe all the other cards are trying to output a resolution higher than the monitor can handle?

I'm not sure why the GeForce works in the BIOS though, I mean it's awesome that it works, but I kinda want to find out why the other cards don't display anything in the BIOS...

Silver_Pharaoh wrote on 2025-03-26, 01:57:

Sorry, not sure how to edit posts, (all I see is the delete post option?) […]
Show full quote

Sorry, not sure how to edit posts, (all I see is the delete post option?)

So I tried the ATI All In Wonder 9200SE, and the Radeon VE PCI card (which apparently is dead) both had no difference.

So I tried the GeForce 440MX with a DVI to VGA adapter and lo and behold I see the BIOS and full screen DOS works!

The modern monitor reports 1080P as the resolution. Maybe all the other cards are trying to output a resolution higher than the monitor can handle?

I'm not sure why the GeForce works in the BIOS though, I mean it's awesome that it works, but I kinda want to find out why the other cards don't display anything in the BIOS...

It's probably going to be hard to deduce what may be happening as your adapters are probably "black boxes" in that they probably don't have clear docs/manual as to what they do specifically nor, I suspect, would they have any configuration options.

IMHO, since we know (please correct me if wrong) that

a) the cards all work when connected over VGA directly to a TV or monitor
b) the results with "black boxes" adapters are inconsistent

I would suggest considering getting a known reliable, documented an configurable adapter, namely the Extron RGB DVI 300 or Extron RGB HDMI 300 (variants that converts VGA to DVI or HDMI respectively, you can use an inexpensive passive adapter for DVI to HDMI conversion, if needed ). These are highly recommended. You can search on vogons.org for some opinions. One of the easiest places to get one is the usual worldwide auction site, IMHO (often significantly under 100 $US with shipping within the continental USA).

darry wrote on 2025-03-27, 00:18:

It's probably going to be hard to deduce what may be happening as your adapters are probably "black boxes" in that they probabl […]
Show full quote

Silver_Pharaoh wrote on 2025-03-26, 01:57:

Sorry, not sure how to edit posts, (all I see is the delete post option?) […]
Show full quote

Sorry, not sure how to edit posts, (all I see is the delete post option?)

So I tried the ATI All In Wonder 9200SE, and the Radeon VE PCI card (which apparently is dead) both had no difference.

So I tried the GeForce 440MX with a DVI to VGA adapter and lo and behold I see the BIOS and full screen DOS works!

The modern monitor reports 1080P as the resolution. Maybe all the other cards are trying to output a resolution higher than the monitor can handle?

I'm not sure why the GeForce works in the BIOS though, I mean it's awesome that it works, but I kinda want to find out why the other cards don't display anything in the BIOS...

It's probably going to be hard to deduce what may be happening as your adapters are probably "black boxes" in that they probably don't have clear docs/manual as to what they do specifically nor, I suspect, would they have any configuration options.

IMHO, since we know (please correct me if wrong) that

a) the cards all work when connected over VGA directly to a TV or monitor
b) the results with "black boxes" adapters are inconsistent

I would suggest considering getting a known reliable, documented an configurable adapter, namely the Extron RGB DVI 300 or Extron RGB HDMI 300 (variants that converts VGA to DVI or HDMI respectively, you can use an inexpensive passive adapter for DVI to HDMI conversion, if needed ). These are highly recommended. You can search on vogons.org for some opinions. One of the easiest places to get one is the usual worldwide auction site, IMHO (often significantly under 100 $US with shipping within the continental USA).

Thanks for the list, I was looking up what others recommended, and I came across a mention for the Extron and others seem to like the OSSC (think I got that spelt wrong)

I'll see if I can source one on that auction site, hopefully it's not the usual shipping cost to get it to Canada 😅

OSSC is ok for DOS but it can be intimidating to get it working.. It has a lot of options and they need to be tweaked specifically for each monitor.

A simpler path is to locate an LCD with VGA input. These are usually listed for free in local marketplaces because they're old and kinda useless for today's machines.

wbahnassi wrote on 2025-03-27, 02:29:

OSSC is ok for DOS but it can be intimidating to get it working.. It has a lot of options and they need to be tweaked specifically for each monitor.

A simpler path is to locate an LCD with VGA input. These are usually listed for free in local marketplaces because they're old and kinda useless for today's machines.

That's one option, but considering the fact that OP mentioned having space constraints and the fact that OP already has a decent monitor, it is, IMHO, less expensive and more practical to get a decent and inexpensive scaler, like the Extron .
An OSSC is an option with sharper "scaling" (actually line multiplication), but it is more expensive, more complicated to set up and less compatible with some monitors (those that are not tolerant of legacy and/or non-standard timings).