[QUOTE=ewmayer;544110]Good thought - tried that, the board-nearest hdmi port on the R7 was uncovered, i.e. the previous owner had likely used it the same for driving the gfx.
[/quote]
It still might be a preference in the BIOS. What is the board make and model so I can reference a downloaded manual?
[quote]

Tiny bit of progress - now the num-lock key lights up a few seconds after power-up, but still nothing on the monitor, and I double-checked that hdmi-to-vga-to-monitor connector chain.
[/quote]
That is progress.
[quote]

One other thing occurs to me - I made no attempt to format the new SSD I bought, just hooked it up to power and sata, figuring any needed formatting would get done after the bootloader read the Ubuntu image on the USB I plugged in. Is that correct?
[/quote]
Ubuntu will take you through formatting the SSD,
[quote]
And, how do I clear the CMOS via the jumper - jump it during power-up?[/QUOTE]

No! Disconnect the power cable from the wall and after 30 second jump the clear CMOS for 30 seconds -- but I am not sure this is necessary. There might be a graphics selection option in BIOS -- you could try loading "defaults".

From the manual:

[QUOTE]Integrated Graphics (Note)Enables or disables the onboard graphics function.

Auto The BIOS will automatically enable or disable the onboard graphics depending on the graphics card being installed. (Default)

Disabled Disables the onboard graphics[/QUOTE]

I looks like either way that when the GPU card in inserted it takes over as the primary video.

Have you checked all the plugs are snugly plugged into the PSU?

[QUOTE=paulunderwood;544113]It still might be a preference in the BIOS. What is the board make and model so I can reference a downloaded manual?[/QUOTE]

It's a Gigabyte "GA-AB350-GAMING 3" mobo.

[QUOTE]No! Disconnect the power cable from the wall and after 30 second jump the clear CMOS for 30 seconds -- but I am not sure this is necessary. There might be a graphics selection option in BIOS -- you could try loading "defaults".[/QUOTE]
The latter would be a neat trick, since my problem is that I can't access the BIOS. ;)

So with all external power disconnected, the CMOS reset is effected using power from the onboard battery?

[QUOTE=paulunderwood;544115]From the manual:[/QUOTE]

Did you go back to my link re. the mobo/cpu-bundle I bought to find that?

[QUOTE]Have you checked all the plugs are snugly plugged into the PSU?[/QUOTE]

Yes, everything is firmly plugged in, and all plugs have latches that snap into place, so it's more or less foolproof.

Also tried Mihai's idea, plugged a 3.2 mm (or whatever it is) headphone jack into alternatingly the Line Out and Rear Speaker Out coax plugs on the mobo back panel - no beeps detected on ensuing power-ups.

Getting back to the CMOS-clear, with power cable unplugged, can I use a small pair of pliers to bridge the 2 metal pins? Or maybe a spare 2-pin system power switch I have here, plug that into the CMOS pinout and click and hold the power-on button for 30 seconds? The alternative is to break open the plastic clamshell housing my Odroid C2, which has a 2-pin jumper inside that I could borrow.

[QUOTE=ewmayer;544117]
Getting back to the CMOS-clear, with power cable unplugged, can I use a small pair of pliers to bridge the 2 metal pins? Or maybe a spare 2-pin system power switch I have here, plug that into the CMOS pinout and click and hold the power-on button for 30 seconds? The alternative is to break open the plastic clamshell housing my Odroid C2, which has a 2-pin jumper inside that I could borrow.[/QUOTE]

[U]After unplugging the wall plug for 30 seconds[/U], anything to short the clear cmos jumpers for 30 seconds will do it, even a screwdriver if you have a steady hand.

(I found the manual)

What do the diagnostic LEDs show? ref page 19 / section 18

[QUOTE=paulunderwood;544118][U]After unplugging the wall plug for 30 seconds[/U], anything to short the clear cmos jumpers for 30 seconds will do it, even a screwdriver if you have a steady hand.[/QUOTE]
OK, if an when I try this: first unplug wall power for a full minute, then bridge the jumper for a similar timespan.

[QUOTE](I found the manual)

What do the diagnostic LEDs show? ref page 19 / section 18[/QUOTE]
On power-up, the LEDs briefly light up and then go off, in the following order: DRAM -> BOOT -> CPU -> VGA. They are all off afterward, and it looks like the system is reading the boot USB, because the LED on that goes into bursty read-activity-indicating mode. Just nothing comes up on the attached monitor.

[QUOTE=ewmayer;544117]
Also tried Mihai's idea, plugged a 3.2 mm (or whatever it is) headphone jack into alternatingly the Line Out and Rear Speaker Out coax plugs on the mobo back panel - no beeps detected on ensuing power-ups..[/QUOTE]

You'll have to connect a speaker to 4 pins in the F_PANEL jumpers (where the power on/off jumpers are). That is where you'll hear the audio beeps. This cheap speaker with 4 pin connector is found in many cases (if you have any old cases lying around).

Before you drive yourself batty, please verify that your setup actually includes integrated video. I know the motherboard has ports, but they are (most likely) only there to route the signals from graphics cores integrated with the CPU. And the R5 1500X doesn't have integrated video.. So, unless there is a separate graphics chip on the motherboard (highly unlikely), you are going end up using one GPU for display. Not a huge deal; 2d desktop barely impacts compute performance.

[QUOTE=Prime95;544121]You'll have to connect a speaker to 4 pins in the F_PANEL jumpers (where the power on/off jumpers are). That is where you'll hear the audio beeps. This cheap speaker with 4 pin connector is found in many cases (if you have any old cases lying around).[/QUOTE]

The only old case I have lying around is the one housing my Haswell+R7 system. :) But it seems the LEDs Paul asked about provide the needed diagnostics, yes?

[QUOTE=sdbardwick;544122]Before you drive yourself batty, please verify that your setup actually includes integrated video. I know the motherboard has ports, but they are (most likely) only there to route the signals from graphics cores integrated with the CPU. And the R5 1500X doesn't have integrated video.. So, unless there is a separate graphics chip on the motherboard (highly unlikely), you are going end up using one GPU for display. Not a huge deal; 2d desktop barely impacts compute performance.[/QUOTE]

The mobo manual says this:
[quote][b]Onboard Graphics[/b]
Integrated Graphics Processor:
- 1 x DVI-D Port
- 1 x HDMI Port[/quote]
But ATM the hdmi cable to the monitor is plugged into the bottom port of the Radeon 7.

[QUOTE=ewmayer;544120]OK, if an when I try this: first unplug wall power for a full minute, then bridge the jumper for a similar timespan.


On power-up, the LEDs briefly light up and then go off, in the following order: DRAM -> BOOT -> CPU -> VGA. They are all off afterward, and it looks like the system is reading the boot USB, because the LED on that goes into bursty read-activity-indicating mode. Just nothing comes up on the attached monitor.[/QUOTE]

Is it CRT or "flat-screen"? Like me you are using a VGA->hdmi converter. I have a blue light that lights up on my monitor when it gets a signal.

You might have ultra-fast boot which might by-pass all BIOS output and go straight to boot (although you should get a no OS message). This sort of boot should be undone once you have cleared cmos -- after which enter BIOS and set the date and time.

[QUOTE=paulunderwood;544125]Is it CRT or "flat-screen"? Like me you are using a VGA->hdmi converter. I have a blue light that lights up on my monitor when it gets a signal.[/quote]
It's a flat-panel monitor, green LED indicates signal, amber means it's in sleep mode, which is the default when no signal is detected. LED has remained amber the whole time, now I've plugged back into the Haswell system to monitor jobs there (I forgot to enable the haswell's wifi before unplugging the monitor/keyboard/mouse to hook up to the new build, thus no remote access capability).

[quote]You might have ultra-fast boot which might by-pass all BIOS output and go straight to boot (although you should get a no OS message). This sort of boot should be undone once you have cleared cmos -- after which enter BIOS and set the date and time.[/QUOTE]
OK, unplugged power, waited a minute, bridged CMOS-reset jumper with tip of needlenose pliers for over 30 sec, plugged back in, on ensuing power-up the diagnostics LEDs light up in a slightly different order than before, now see [DRAM -> BOOT -> CPU] with that trio cycling several times before reaching the VGA LED, after which all off, but still nothing on monitor. Just by way of flailing, powered down, again did reset-CMOS, but this time switched the hdmi plug from the R7 back to the onboard-gfx one, again power-up, LEDs again light in the above modified order, again no joy at the end.

And that's enough frustration for one day - tomorrow will again pull the R7, reset CMOS, retry with onboard-gfx, if that fails will swap in one of the other of the 3 R7s I bought. I shoulda stuck to DIY carpentry. :(

You might still need a GPU card if the CPU has no graphics capability -- it will not react with the onboard graphics.

Everything looks good apart from the lack of signal...

Did you unplug the monitor when you switched it from the haswell system? Try unplugging the hdmi and unplugging the monitor from the wall. After a minute plug it all back in and switch it on. Then boot the your AMD box.

Other than this, it looks like a duff motherboard or CPU. It might be worth getting hold of a cheap CPU such as a [URL="https://www.newegg.com/amd-a6-7th-gen-a6-9500/p/N82E16819113454"]A6-9500 for 50 bucks[/URL] (with integrated graphics so that you can use the onboard graphics) to see if that solves the problem. Maybe first re-reseating the existing CPU -- why did the guy who sold this kit to you reseat the CPU if he was not having problems? Not a maintenance thing to do. If it does turn out to be the CPU (or motherboard) that is the problem the seller should refund you proportionally for the value.