F12 Diagnostics screen (ePSA) is the only screen I've found with the scrambled display I posted.  Never occurred to me to boot with hard drive disconnected.

@DE54   - Did you try clearing BIOS?

@DE54I agree with @RoHe , try clearing the BIOS.

No other issues with screen displays in BIOS, Windows desktop, applications, browsers, games, etc...

Wasn't BIOS.  I had a new Samsung monitor ordered, just arrived.  Hooked it up, F12 - Diagnostics (ePSA) - displays perfectly!  SupportAssist checks for drivers, finds drivers AND installs drivers, no problem!  Still getting blue loading bar under Dell logo on splash screen though. 

Apparently new motherboard had an issue with the monitor that the old motherboard didn't.  Previous HP desktop never had a problem with the monitor either.

So new Samsung monitor - no problem with Diagnostics (ePSA) screen, still problem with Dell splash screen

Old HP monitor - problem with both Diagnostics (ePSA) screen and Dell splash screen

How is/was the monitors connected (HDMI, DisplayPort, etc.) and where is/was the monitors connected (integrated onboard or discrete graphics card)? Do you have a different video cable you can try?

Have you tried removing the add-in video card and connecting the monitor to one of the onboard Intel HD Graphics ports? That should tell you if the add-in video card is the problem...

@RSimmons09 I don't understand how a single 8GB memory module can be dual channel. Are you looking at the Memory tab in CPU-Z? You may want to try a program called HWiNFO64. I am not positive, but I believe if you have a matched pair and a single memory module the system will run in single channel.

@Vic384

I ran HWiNFO64 and it also shows 40GB total in dual channel mode.

Since my original configuration was a single 8GB DDR4 SDRAM in DIMM1 which ran in dual channel mode I thought to try the matching 16GB DDR4 2666 in DIMM1 & 2 and the single 8GB DDR4 2666 in DIMM3. It shows 40GB dual channel using both CPU-Z and HWiNFO64.

Sorry if this is multiple posts but don't see my earlier post.

This is strange. I always thought that dual channel requires pairs of memory modules and was not possible with a single memory module. See this article: https://techguided.com/single-channel-vs-dual-channel-vs-quad-channel/

It is good that your memory is running in dual channel mode, I just don't understand the results you are getting.

@Vic384    I'm also suspicious that it's dual channel mode. I wonder if those apps are only reporting the matched pair. ?  The article you linked says: 

"...installing three sticks of RAM would be utilizing two of the sticks in dual channel mode and one of the sticks in single channel mode."

I suspect that having 4 sticks, all running in dual channel mode, would be faster and more efficient than 2 in dual channel and 1 in single channel mode.

@Vic384   - Don't know how to explain the OP's statement that with only one module installed, RAM was reported as running in dual channel mode.

And I'm not going to pull one 8 GB module out of my XPS 8930 to test this out...

@RoHe I would concede the apps only reporting the matched pair but what about the OP reporting that the single memory module also reporting dual channel. 

@RoHe My XPS 8910 came with a single 16GB memory module and I am pretty sure CPU-Z indicated single channel until I upgraded by adding another 16GB module.