That's not correct. Only the X55xx CPUs that apple used in the DP 4,1 are lidless. All the other E55xx, X55xx, or W55xx CPUs in the marketplace have a conventional Integrated Heat Spreader (lids)
The X5677's should run RAM @ 1333MHz. I went with that CPU as it has the fastest factory clock speed you can get for a cMP but only costs 1/3rd what the X5690's are going for. For my needs (some hobby photography with Lightroom, occasional HandBrake and a little gaming in boot camp) it should be the best balance for my budget.
I just purchased mine from Craig's list. I feel I didn't get the best deal. Or did I ? It's a 2009 2x2.66 w 5770 only 6gb of ram for $1100. It is mint. But what's really weird is it doesn't have the. Serial number sticker under the PCI slots. It's almost like it was never put on. The surface was perfectly clean. The serial in the OS is legit from apple and didn't have a special firmware. I thought maybe it was a refurb. Odd.