You want to rule out everything else before you just decide that the Mobo is dieing, since your memory seemed to pass testing. The easiest thing to do, would be trying to remember, what you installed in the way of new hardware, or software (including driver software), right before this error started to occur. Since I previous mentioned that this error is usually x86 based, software would be 32bit (but that probably encompasses all of the software on your system, with the exception of your OS.) If you can eliminate something new, you may easily determine the cause of the error if it is software or hardware based, by removing the hardware, or software, and seeing if the problem goes away. Also, double check the crash error log in Win7, to see if by chance, windows has logged any errors that it may have recovered from, before the BSOD with the x07f code. There is a possibility that the errors got logged into a crash dump file. The dump files should be located in your “C:\\Windows\\Minidump” Directory.
If you see an error that you can identify as one of these BSOD, find the associated “crash Dump” file (probably the newest). If you can find this, put it into a “zip” file (OCN won’t allow you to upload a dump file, but a zip file is acceptable), and upload it with a post. I will take a look at the file, as my time permits, and see if I can point you in the right direction. No guarantees… but I will try.