HDMI output not working after reinstalling NVIDIA Quadro m620 drivers.

[AVLien]

So, I was having some sporadic BSODs, so I decided to run driver verifier to get to the bottom of it (BTW, if you don't know what you're doing[edit]). It turns out that the NVIDIA driver I had installed was not behaving, so I uninstalled/reinstalled it from their drivers (Premier Pro was fussing at me to do this anyway). I haven't had a crash in about 48 hours, so it seems that issue is resolved.

In classic fashion of (all) computers though, one problem solved caused a new one to arise. Now my HDMI output is not detecting my external monitor.

Trobleshooting I have already done:

• I have reinstalled the drivers again
  • From HP
  • NVIDIA directly, to no avail.
  • The last time, I did a clean install (via the checkbox in the installer) and made absolutely sure that I had removed every last piece of NVIDIA's software.
• I still have access to the NVIDIA control panel and the Nview desktop software, but everything acts as though nothing is connected.
• I have also verified the cable is good.
• I have verified that the monitor input is working and detecting connections.
• Windows is only detecting the internal display.

A few notes that may (or may not) be helpful:

• Odd thing #1: the monitor acts like it's connected, but not receiving anything (i.e. it doesn't go into standby or shut itself off as it would if nothing was connected)
• Odd thing #2: when the machine was shipped, the Quadro m620 would not acknowledge the internal display at all. It was as if it did not exist in it's world (speaking hardware bus-wise). Now it shows up in the Physx panel. Maybe unrelated, but it didn't do that before.
• Odd thing #3: Without manually installing the drivers, the display will be detected as a generic display device, which is something I haven't seen before (not since circa Windows Vista/XP anyway). It will also not detect the monitor with the generic driver.

[AVLien]

This machine has lost it's damned mind. I resolved the issue. I still don't get how, but here's what I did (the first 13 steps had no noticeable effect, but they were the logical course of action to troubleshoot the issue)

.

1. No really, I should understand why...but I just don't...Downloaded [edit]
2. Disabled WiFi (alternately, you could just disable/postpone Windows Update) to prevent automictic reinstallation.
3. Booted to Safe Mode.
4. Ran DDU to remove NVIDIA drivers (reg keys, etc) completely.
5. Rebooted.
6. Started up Windows normally.
7. Manually installed NVIDIA drivers.
8. Reenabled WiFi.
9. Rebooted.
10. Started up Windows normally.
11. For some reason, Windows updated the driver again from Windows Update. So I...
12. Rebooted again.
13. Nothing. Still not sending a signal to the HDMI.
14. Here's where it gets anomalous: I rebooted to check the BIOS settings, opened the 3rd Party Option ROM Management menu (which was empty), I changed nothing (see: "...empty...") and exited that menu, which automatically...
15. Rebooted the machine.
16. When the machine began to load Windows, the monitor worked.

If anybody reads this who knows more than I do about HP BIOSs, please help me understand how not changing anything at all fixed the problem that 10 driver reinstalls, 30 some odd reboots, and everything else I could possibly think of in drawing on three decades of hardware tech experience couldn't (see figure). I'm so confused by this I had to write that last bit in magenta Comic Sans, that's how seriously I am befuddled by this...