P5N-E SLI with Q9550

Check out:
http://support.asus.com/cpusupport [...] uage=en-us
That CPU is a 45nm quad, not supported by your 650i motherboard - I'm surprised it works at all!! Your mobo only officially supports 65nm quads (Q6600 etc). 650i boards will take a 45nm dual core (E8x00), but not the Q9x50s - I think it is to do with the addressing of the larger 12Mb cache, 650i's can't do it. Your speed issue might be to do the motherboard setting a default 1066 QFSB as it thinks its a 65nm quad? You may get the correct speed buy upping it to 1333 QFSB however you will never get the full potential of the chip on that board as it won't be able to address the full amount of cache and you might have other issues.

Never by brand new combos off Ebay. The prices are never that competitive if you shop around and you are much better getting from a non-ebay company as the support is likely to be much better in the event you have a problem. First off contact the Ebayer and tell them your problem and ask them to pick the board or board and chip up and refund you for it.
For a Q9x50, you need a board based upon an nvidia 7x0i chipset or intel P35 (I think only the newer P35s support 45nm Qs so check) or P43/P45/X38/X48. Whether you go Intel or Nvidia depends on whether you need SLI. If you don't need Nvidia SLI or plan to run a single graphics card I would get an Intel chipset board as they are better this generation.

I just put a Q955O ON MY P5N-e SLI with the 1403 Bios. It works fine but the core voltage is at 1.403 and I can't overclock anything, including ram. The CPU seems to run a little hot. Don't know if I need new motherboard.