If you had another board or two and another psu you could figure out if it is just the cards or the two boards just being picky. This is a good reason to collect or hoard a few spares not knowing if something is going to quit or arrive doa.

Do you use the same PSU for both?

Two different PSU's of the same model.

I suppose I need to buy a 3rd PCI video card and see what happens.

But the system boot up anyway even without the video signal?

386SX wrote:

But the system boot up anyway even without the video signal?

Not really sure. I'm not that adept at interpreting sounds, but it does seem like it's working. I usually don't let it go very far, though. It only takes a few seconds to realize the video signal isn't going to come through.

AllUrBaseRBelong2Us wrote:

386SX wrote:

But the system boot up anyway even without the video signal?

Not really sure. I'm not that adept at interpreting sounds, but it does seem like it's working. I usually don't let it go very far, though. It only takes a few seconds to realize the video signal isn't going to come through.

Try to see if the hard disk is usally running as long as it does when you get the signal. If it does maybe could it be the monitor having some problems?
If it does not, I would exclude to use any common components (ram or disk or pci cards) to see if something is faulty hanging both systems. If it hangs anyway, well I would try another vga too.

AllUrBaseRBelong2Us wrote:

386SX wrote:

But the system boot up anyway even without the video signal?

Not really sure. I'm not that adept at interpreting sounds, but it does seem like it's working. I usually don't let it go very far, though. It only takes a few seconds to realize the video signal isn't going to come through.

Have you tried a different monitor?

PSU has already been mentioned, since both are the same model it may be something about those.

I'd suggest you give your systems a bit more time to boot (maybe 20 or 30 seconds) and wait a bit, sometimes it can take a while longer for some reason before it starts displaying an image.

Have you hooked up a PC-speaker? If it gives any beeps, that will help you figure out what's the matter.

The monitor is definitely fine. But I do have some new information now. I finally got around to putting my pentium pro system in a case, and I noticed something with the power led. When I'm not going to get video, the power LED flashes slowly on and off. When I am going to get video, the power LED is solid. It's much quicker to boot now because I can just watch the LED and hit the reset button a couple of times until I get a solid LED.

If you find some info/manual of you motherboard maybe there'll be some led status info about the slow led light. Is the power cable outside the power supply connected directly to the wall or with a multiple plugs?

I had a similar issue with my pentium rig. With some pci cards it won't display anything. I've found that my motherboard is faulty, most probably due to old capacitors. The regulator is drawing too much current even without load and I'm suspecting that in some circunstancies the psu just can't give that much power. I'm waiting to order caps for a full recap.

I'll sugest trying your cards in a new system if it's possible.

It's a VS440FX board. I scanned through the 72 page manual, but didn't see anything about a flashing power LED. Might notice it if I read more carefully, but upon the suggestions of some forum members, I have a couple other PCI video cards on the way. So I'm going to try those out and see how they do. If they don't solve the problem, I'll revisit the boards as potential problems.

UPDATE!

And the weirdness does not cease...

I got one of the two new video cards I ordered in, put it in the pentium pro system, and got the exact same problem. Had to hit reset a couple times before the system would boot.

My processor is a Pentium Pro 180, so the bus speed was set to 60MHz. On a whim, I decided to see what would happen if I changed the bus speed to 66MHz. It boots every time now. The BIOS sees the processor as a Pentium Pro 200, and the system boots every single time without a hitch. Just being curious, I decided to set the jumpers for a Pentium Pro 166 (as it also uses 66MHz bus speed), but the system would not boot at all then. So I set it back to 200, and it runs perfectly as a 200. I don't know if there will be any negative long term effects from the overclock, but I haven't noticed any problems yet.

No idea why it works fine as a 200, but it does.

AllUrBaseRBelong2Us wrote:

UPDATE! […]
Show full quote

UPDATE!

And the weirdness does not cease...

I got one of the two new video cards I ordered in, put it in the pentium pro system, and got the exact same problem. Had to hit reset a couple times before the system would boot.

My processor is a Pentium Pro 180, so the bus speed was set to 60MHz. On a whim, I decided to see what would happen if I changed the bus speed to 66MHz. It boots every time now. The BIOS sees the processor as a Pentium Pro 200, and the system boots every single time without a hitch. Just being curious, I decided to set the jumpers for a Pentium Pro 166 (as it also uses 66MHz bus speed), but the system would not boot at all then. So I set it back to 200, and it runs perfectly as a 200. I don't know if there will be any negative long term effects from the overclock, but I haven't noticed any problems yet.

No idea why it works fine as a 200, but it does.

A 20 MHz overclock is nothing to worry about with a gold top Pentium Pro as long as the heat sink has a fan but at 233+ MHz they start to use alot of power, this is however more of an an issue for dual CPU boards.

Skyscraper wrote:

AllUrBaseRBelong2Us wrote:

A 20 MHz overclock is nothing to worry about with a gold top Pentium Pro as long as the heat sink has a fan but at 233+ MHz they start to use alot of power, this is however more of an an issue for dual CPU boards.

Unfortunately, it's a passive heatsink, permanently bonded to the processor with Arctic Silver Thermal Adhesive. It's a decent size heatsink, but no fan--just an exhaust case fan near it.

I'd still love to know why it works perfectly at 200, but not at 180.

AllUrBaseRBelong2Us wrote:

Skyscraper wrote:

AllUrBaseRBelong2Us wrote:

A 20 MHz overclock is nothing to worry about with a gold top Pentium Pro as long as the heat sink has a fan but at 233+ MHz they start to use alot of power, this is however more of an an issue for dual CPU boards.

Unfortunately, it's a passive heatsink, permanently bonded to the processor with Arctic Silver Thermal Adhesive. It's a decent size heatsink, but no fan--just an exhaust case fan near it.

I'd still love to know why it works perfectly at 200, but not at 180.

You should figure out a way to get some airflow over that heatsink or the Pentium Pro will run very hot. At 200 MHz a Pentium Pro 256KB or 512KB is rated at close to 40W and its not much less at 180 MHz.

The exhaust fan could perhaps be enough depending on how much air it moves and how close to the CPU it's placed.

Skyscraper wrote:

You should figure out a way to get some airflow over that heatsink or the Pentium Pro will run very hot. At 200 MHz a Pentium Pro 256KB or 512KB is rated at close to 40W and its not much less at 180 MHz.

It's running at a temp where if I touch the fins for more than a second or two, they'll burn me. Haven't come up with any way to attach a fan, but maybe something will present itself.

Just thought of something in common between the pentium pro system and the 486 system. They both use the same 60ns FP RAM. 2 32MB sticks in each board. I wonder if that could have anything to do with the issues I had. It's new RAM, purchased from one of the memory manufacturers that still manufactures RAM for vintage machines.

Oddly, whatever the cause of the PCI video card issues, it turns out the solutions for each machine were the following:

1) 486 machine: use a Vesa Local Bus video card instead of PCI. Problem gone.
2) Pentium Pro machine: overclock the processor from 180 to 200. Problem gone.

In the case of the 486 it could be a buggy PCI implementation. In motherboards with both PCI and VLB slots one of them is usually problematic.