I attempted to upgrade to two X5690s.  I was unsuccessful.  In fact, at the moment I'm worse off than I started because now the RAM in slot 1 doesn't show up, no matter which chip I put in the slot.  And the red light is on.  I've heard this could be related to the tightness of the heat sink, but I suspect I fried the slot when I didn't have a RAM stick fully seated.  So I put the original CPUs back in it, and its running fine, minus RAM slot 1.
I couldn't get the machine to boot, and when I finally did, I got the same kernel error black screen over and over, even when trying to boot to USB.  I got the white apple screen and the chime.  I'll try and dig up the picture I took of the error and report back.
I am going to try it once more tonight.  If I can't get it, I'm going to send it off to an upgrade service on eBay.  They are pricey, but the time investment involved is worth it alone.
My questions are these:
My CPUs were from eBay from two different vendors.  They appear to be the same, and have the same writing on the IHS, but I have no way of 100% confirming that they are a "matched pair".  Any tips?
Also, since these were used one of them could be bad.  I haven't found a decent way to to confirm that though, other than to check for damage to the gold plates.  I can't see any.   Does anyone know a way to test a CPU?
Should I upgrade one CPU with the 2nd slot empty, and then upgrade the 2nd CPU?
And lastly, should all of this fail, which I'm expecting it will, what should I look for in a good CPU upgrade service?  Or is there a recommendation or preference?
Thanks so much.  You all on this forum have been the only thing to keep me sane at times.