3010 RAM Slot Dead

Have you tried reinstalling the old CPU to see if the RAM problem disappears? My point is that the only way that slot could go bad by a simple CPU upgrade is if the CPU has a bad memory controller, which would give that exact symptom. Now is it possibly a bad MB, sure but that would be quite a coincidence. The old adage is it is never the CPU until it is. I have seen bad memory controllers in CPUs before.

Does the i7 work with only 1 RAM module? Point being that the i7 may not be compatible with the MB.

If you accidentally bent a cpu socket pin during cpu swap, that can render one or more DIMM slot not working.

You can carefully remove the newly swapped i7 and take a very close look at socket pin.  Even a tiny bit focal irregularity can suggest a socket pin is bent.

I have a board that has this issue due to bent socket pin (I got the board as is) , and I heard from some one with more experience than I had similar issue on his board.  one or two DIMM slots dead.

• I agree with the other posts, but I have one thing to add. If putting the old cpu back in solves the problem, you might need a bios update. I’ve read on several sites that bios updates are sometimes required to do cpu upgrades. I know I had to do it on my son’s old Dell because I was upgrading from a 32 bit cpu to a 64 bit cpu.

Optiplex 3010 Tech Guide 

Top listed CPU for the 3010 is I5-3450.  3010 is limited to 3rd gen CPU, not 4th.  There are users in userbenchmark using the I7-3770.

"I bought a new i5-4590 and replacement board for cheap and all was good. Today I made a small CPU upgrade to a i7-4770"

Also considering the possibility we're talking about a 3020 and not a 3010.