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.