Hey Arulin, Many question so I will try to answer as much as I can. would a 780m GTX pulled from a Clevo not post at all on a Alienware x17m R3? That is possible, if you have the wrong BIOS running, the wrong drivers,... Many things can add to this. Is there any reason why a Clevo 780m GTX be any different then a Alienware 780m GTX except for the bios? Nope, Clevo uses univeral cards or generic as well they should work fine in Alienware. Would CPU heatsink grease cause any issues on the memory chips instead of using heat pads? I do not understand this question well can you elaborate. Yes thermal grease should not be used as a thermal link on the memory chips, if you see some there clean them with a very fine soft brush and dab of alcohol on a cotton and without pressure wipe the chips off. When five and six beep codes happen from a freshly installed MXM card is that a sign that the card is bad? That beep code is usually a sign of bad RAM stick or Dimm slot, try uninstalling some ram and retest again. Best option here is to leave one stick in and do a CMOS reset then try again. If a mxm card is working, no matter what bios is on it will it still POST? Unless the card is shorted the laptop should post, the reason why it is not posting i think is from ram or something else, try unplugging the card and revert everything to original, does it post then. If yes boot couple times and do clean restarts, shut down uplug, cmos and install the card boot into safe mode and delete all drivers and start from scratch. If you can not boot at all then I think the answer is "BAD GPU" Is there any reason why a pulled 780m GTX from a Clevo would not work in an Alienware x17m R3? No, it should work fine if the card works fine, inspect it physically any missing chips or damaged, look on google for a reference on how the chips should look like. Send it back and get your money back if you have the option for a refund if not then try to express buyers protection on ebay. Goodluck.