I preface this by saying that I know my system is over 5 years old, but it worked the way I wanted to through Win 7, 8, and 8.1. The difference is that I had not upgraded the AMD software in awhile, and upgrading to Win 10 forced the issue. I've tried many ways over the last 4 days to fix this, and I'm at a loss now, even with extensive Googling.
I have a Gateway DX4300 with an upgraded CPU (from the original, but still not very recent) that has ATI Radeon HD 3200. The gfx card is an ATI Radeon HD 5550 (AMD Radeon HD 5500 Series driver). I have two monitors plugged into the card, both Gateway HX2000, one DVI-D, the other VGA. I also have an old Dell 1905FP VGA plugged into the onboard.
When I first upgraded to Win 10, 4 days ago (not beta), with the forced updates of the gfx card and other devices, the three monitors worked fine, as they always had, with extended desktop, the Device manager recognized all three monitors by name, and the two display drivers were correct. As Windows update continued and the system restarted, the onboard was no longer recognized, the two Gateways reverted to some generic version on the device manager (sorry, didn't write down which one).
After many hours trying to download software that didn't fix the problem, I did a clean install of Win7 Home Prem that came with my computer. Unfortunately, it also relied on the newer AMD software versions (and the old one on the Gateway site is a broken link), and the problem remained. Once again, this time a clean rather than upgrade install, I put Win10 on the computer. Again, all three monitors were detected, correctly named in the device manager, and both the display adapters (3200 and 5500 series) show up as they should, and I again had 3 monitors with extended desktop.
Until the restart ...
Now I'm back to the two Gateways on DVI-D and VGA, and no third monitor. I've ordered one of those USB monitor converter thingies under the recommendation of a helpful guru, but I'm still both annoyed and stymied why the original configuration worked with Win10, but then the restart messed it up so the onboard doesn't work and the third monitor is not detected (unless I pull the card, use the onboard, replace the card, etc. with every restart ... no.)
Any thoughts, ideas, criticisms on what I've done wrong, etc.? (And no, I can't afford any computer or card upgrades at this time. I just want to fix the software problem that only came about with the upgraded software that broke what was working well for me before.)
(TLDR: Win10 forced upgrade of AMD software; 3 monitors worked until restart, then onboard is not working, even though enabled in BIOS and worked before just fine in 7, 8, & 8.1)