Hello all, I don't know how to describe my issue better in one sentence. Sorry for wall of text in front, details follow...

Today I tried installing Windows 98 on this computer, everything went fine. I turned it off and few hours later when I turned it on back to finish install there was no image on monitor. I don't get post screen or anything.

Configuration is

CPU: Celeron Tualatin 1300
Motherboard: PCPartner 815EPBAS3-T217CA (only one I have that supports tualatins 😒)
RAM: 256 MB PC133 SDRAM
Graphics card: AGP GeForce 4200 Ti 64 MB (Leadtek)

I also have ISA/PCI post card and it shows POST codes progressing as normal, beeps one time on post, everything looks normal except monitor remains in stand by.
I've tried both VGA and DVI connectors. Over VGA it remains in standby, over DVI it turns on, says "No signal" and goes to stand by, then again turns on, says "No signal" and so on without end...

I have few more AGP cards. GeForce 2 MX 64 MB (also Leadtek), GeForce 2 MX400 64 MB, ATI Rage Fury Pro 32 MB, same story, no image over AGP.
Only one that still shows an image is ATI AIW Radeon 9600 1280 MB.

Only difference between all of these cards is that AIW Radeon has only one notch on it's edge connector (if I'm not mistaken that means it's AGP 2.0 4x 1.5V), while all of the non working ones have two notches which should make them universal AGP 2.0 2x/4x 3.5/1.5V cards (4200 TI is 4x variant, not 8x refresh). Board has universal AGP 2.0 slot. So no problem should be on that front.
GeForce 2 MX has LEDs on it, AGP4X, Error and Power, AGP4x and Power are lit, so at least I can tell it get's powered...
I also tried another monitor and VGA cable, no change.

Any ideas on what could be the issue here here? So far I haven't experienced an issue like this one.

btw.
I also tried PCI Rage XL card (one of recen t chinese ones) and that one also works fine.