Supermicro X9DRI-LN4F+ No Input/Output Error

[n12unix]

I'm facing a weird issue with my Supermicro board, and not quite sure how/why it happened and where to go from here. Here's a bit of background:

• Supermicro X9DRI-LN4F+ (Bios ver 3.3)
• 2 x E5-2650V2 CPU
• 2 x 4GB memory

I booted up the board when I first got it - all was okay - I was able to get it to POST, and get into BIOS etc and confirm it the correct CPUs and memory were being reported. Following this, I removed the stock heatsinks, cleaned up the thermal paste, and installed two Arctic Freezer 12s.

Once the new coolers were installed, I decided to try booting up one more time before installing in the case to make sure the fans were running etc. and this is where I'm stuck now. I'm getting 5 beeps plus 1 weird beep after I turn the board on, and no video output through the VGA. Absolutely nothing has changed except removing the stock passive heatsinks and installing the coolers.

I've tried:

• Removing the CPUs and RAM and resetting them both
• Going down to a single CPU and and single stick of RAM
• Installing the old heatsinks back on

According to the Supermicro manual, the 5 beeps is a no input/output error - not quite sure what the 1 weird beep I'm getting after is however. I have attached a video of the beeps for reference.

Would appreciate any suggestions for troubleshooting steps and where to go from here.