Inspiron 5680, adding RAM, won't boot

Sounds like you know what you are doing.  We have all inserted ram incorrectly in DIMM slot at least once before but I have never heard of persistent read/write error of the slot after one incorrect insertion which also affects the other 3 slots.  I can not believe one incorrect insertion would cause a short circuit.  that is quite strange.  I do not think it has anything to do with cmos.

if you have a magnifying glass try to take a look at your DIMM2.  Is there any sign of bent pin?  just curious if you leave all dimm slots empty, what beeps do you hear?  would it be possible that both your new crucial and old DDR4 are somehow acutely damaged in uncanny ways?  Test the ram in another system.  Bad stick would not brick a board afaik.

First, how are you numbering DIMM slots? The one closest to the CPU is probably not DIMM1. DIMM1 is more likely the second slot from the CPU.

Mixing brands of RAM in the same bank (matching colored clips) can cause issues, even if the specs "match".

Keep in mind you can get a RAM beep code if there's an issue with the GPU which has RAM on it too. So see if the video card was accidentally dislodged from its slot or if it's power connector (if it has one) was disconnected while you were installing the new RAM.

Assuming your monitor has a DisplayPort video input, or if you have DP(PC)>HDMI(monitor) or DP(PC)>VGA(monitor) adapter handy, you could physically remove the add-in card and connect the monitor to the onboard DP connector on the PC and boot up.

Remove motherboard battery and press/hold power button for ~30 sec. Then put original RAM module in its original slot, then remove video card, and finally reinstall the battery. Good idea to use a fresh CR2032 battery. Close up and reboot with monitor connected to the PC's DP port.

@redxps630 

Using loupes and a head lamp I do not see any obvious damage to any of the DIMM slots. I tried booting with all empty and I get two beeps indicating no RAM. Unfortunately no way of testing the RAM in another system which would be crucial for trouble shooting.

@RoHe 

I was using the labeling on the mother board itself for DIMM designation. In order to jump the CMOS I had to remove my GPU which was additionally secured with a brace from factory. That was the last thing I tried so when moving around the different RAM sticks beforehand the GPU was secured firmly. I ensured it was properly installed before testing the CMOS jump. I can try what you said but the 9400F does not have discrete graphics. Not sure if that matters, if it does I can also try reinstalling the 8100 which has discrete graphics. My monitor has all of those connections you mentioned.

@wliska  - Didn't know CPU doesn't support onboard graphics. Up to you to decide whether to re-install the old one to test using onboard graphics, especially since I can't guarantee switching to onboard graphics will solve the problem. If nothing else, I'd remove/reseat the video card in its slot, especially since screen stays black.

No offense, monitor is connected to a port the video card, not to an add-in video port? And monitor turns on? 

Have you tried a different pair of video ports on video card and monitor?

Did you put CMOS jumper back on correct pins?

PC was unplugged and did you reset BIOS by pressing/holding power button for ~30 sec after removing motherboard battery, before reinstalling the battery?

Did you try a fresh motherboard battery?

What color is the PSU power LED on back of PC, and what happens when you press the BIST button next to that LED?

Are mouse, keyboard plugged into USB2 ports, not to USB3.1 on rear of PC?

Do you have externally powered USB hub with its own power adapter? Connect adapter to the wall and plug hub into a rear USB2 port. Connect mouse/keyboard to PC via the hub and see if they work now...

@RoHe 

Didn't know CPU doesn't support onboard graphics. Up to you to decide whether to re-install the old one to test using onboard graphics, especially since I can't guarantee switching to onboard graphics will solve the problem. If nothing else, I'd remove/reseat the video card in its slot, especially since screen stays black.

Tried unplugging and removing GPU then reinstalling, still no response from either monitor. I confirmed monitors work on my laptop.

No offense, monitor is connected to a port the video card, not to an add-in video port? And monitor turns on? 

None taken. Yes, both monitors are plugged into the GPU. I don't think I've honestly ever had any connected to the motherboard ports with this PC.

Have you tried a different pair of video ports on video card and monitor?

Yes.

Did you put CMOS jumper back on correct pins?

Yes.

PC was unplugged and did you reset BIOS by pressing/holding power button for ~30 sec after removing motherboard battery, before reinstalling the battery?

Yes

Did you try a fresh motherboard battery?

No, unfortunately car is in the shop, don't have immediate access to a store.

What color is the PSU power LED on back of PC, and what happens when you press the BIST button next to that LED?

Green. When I hold down the BIST button the fans and LEDs turn on. No beeps or flashing on the power button.

Are mouse, keyboard plugged into USB2 ports, not to USB3.1 on rear of PC?

Yes.

Do you have externally powered USB hub with its own power adapter? Connect adapter to the wall and plug hub into a rear USB2 port. Connect mouse/keyboard to PC via the hub and see if they work now...

Mouse and keyboard work when plugged in to my laptop.

Are you doing your testing with 2 monitors connected, or have you tried using only one at a time?

Mouse and keyboard may work perfectly on another PC, but if the USB power circuitry in the 5680 failed, perfectly good devices won't work with this PC. That's why I suggested trying an externally powered USB hub which should provide enough power for the devices connected to the PC via the hub, even if the motherboard USB power circuitry failed.

You can try USB3.1 ports instead of USB2, but I'm not optimistic...

@RoHe 

Are you doing your testing with 2 monitors connected, or have you tried using only one at a time?

Tried both ways and no difference.

Mouse and keyboard may work perfectly on another PC, but if the USB power circuitry in the 5680 failed, perfectly good devices won't work with this PC. That's why I suggested trying an externally powered USB hub which should provide enough power for the devices connected to the PC via the hub, even if the motherboard USB power circuitry failed.

Oh, I see. I do not own one of those.

You can try USB3.1 ports instead of USB2, but I'm not optimistic...

Tried, no difference.

sounds more like a power supply problem.do you have a spare power supply off of an older system for test purpose. dell power supplies though generally reliable can become finicky from power spikes from on the mobo.i've experienced it first hand from a very similar situation on my old inspiron 531

@NTay68 

sounds more like a power supply problem.do you have a spare power supply off of an older system for test purpose. dell power supplies though generally reliable can become finicky from power spikes from on the mobo.i've experienced it first hand from a very similar situation on my old inspiron 531

Unfortunately I do not have another one. This is my first desktop that I've had since the mid-2000's.

@RoHe 

Running out of suggestions...

A powered USB hub is ~$10-$15 on line, but it's starting to starting to sound like the motherboard failed...  

That's what I assumed it was before posting on here. Was just hoping someone a lot smarter than me had a trick up their sleeve to get me out of a pinch. To be honest I already ordered stuff for a new build this morning. I've been wanting to upgrade even further and this is finally my excuse. I originally wanted to build a PC but in 2018 GPU prices were sky high so I opted for a pre-built. At least I learned a lot during this little mishap. I appreciate all of your help. If you come up with anything else I'll gladly try it out for kicks and report back.

If you get a new GPU for your new build, you could try it in here, assuming the PSU is big enough for the new video card.

Keep in mind that it's not so easy to swap motherboards into a Dell case because of the custom wiring between motherboard and front panel. So look around the forum to see if anyone has re-used the case with a non-Dell board and how they wired the front panel

And, you're going to need a new license for Win 10 because the OEM Win 10 license you have now is tied to the Dell motherboard.

Maybe you can get Crucial to take their stick back under warranty, if it doesn't meet the requirements for your new motherboard?

@RoHe To avoid headache I went ahead and got a new case amongst other things to avoid any issues with Dell compatibility. I spent a considerable amount of time researching compatibility before deciding to almost start over from scratch. Sure it may end up costing more but I have been wanting to build a PC from scratch for a long time and will no longer be confined to Dell compatibility issues with future upgrades. Will see if Crucial will take the stick back, if not it was rather cheap and may come in handy in the future.

@RoHe 

Thank you! Going to re-use the 1060 for now assuming its still functional. Researched out every component I ordered today for compatibility as well as future proofing. Should end up as a solid mid-level build focused on gaming with honestly the 1060 being the bottleneck. I appreciate all of your help and input.

Good luck with your new build. Hope it works well for you...

BTW: make sure {whatever} video card you use will fit into the new case, height, length, and width...

BTW: Now that I finally got to see the correct image for this motherboard. (The image in the Service Manual is wrong!!  )

Did you check that the USB2 (#7, green), USB3 (#12, blue), and power connector (#9, white) are all correctly connected  to the motherboard?