Hi @Broxiet,

It sounds like a mainboard issue. But might not conclude that if you have extra components to try.

You mentioned PSU installed, would that be 1 or 2 PSU installed? Can you try 1 each at slot 1 if doesn't work, try on slot 2. Do you have any extra R730 PSU to check with? 

I'm unsure if your R730 mainboard has it, but can you check near the PERC connector on the mainboard, there are 7 tiny LEDs, are they lid? (In between label 23 and 25: https://dell.to/3TdWmCU)

Try disconnecting/removing the CMOS battery.

If issue persist, remove all components except these below and try to turn on the server:

• System board
• One power supply unit
• One processor (CPU) in socket CPU1
• One memory module (DIMM) installed in socket A1
• Left control panel (for power button functionality)
• One backplane card

I've tried booting with PSUs from my other R730s, but no success.

I also checked the LEDs, but during the check I think things are getting worse, as I realized that the moment I plugged in the power cord, a nasty smell like burnt rubber came from inside the server, so maybe something is shorted and overheating.

As for the LEDS, I had LED3 on between 23 and 25, and I also had a IDRAC_USB_DVC LED on between 23 and 21.

hello my friend,

it seems capacitor of the PSU are overheating and burning due to short Circuit, there are also possibilty of the track short or any component of the system board is creating the issue, suggest you to remove the board and power supplies and check with another system board and single power supply, by this you can save rest of the components.

thanks in advance and please let me know the status.

I've located the source of the smell and smoke, an Infineon mosfet and a capacitator arouond CPU2 between 32 and 34. Both are fried during the check. So the conclusion is indeed a MB failure. Thanks for the help @DELL-Joey C @Praveen.Singh , and by the way, is MB replacement the only thing left to do?