Take two and raise it to 68. Assuming that any PC had such an addressing register size (some strange supercomputer, perhaps?) that would be how much said CPU could theoretically address. I've seen worse technical error posted on forums (much worse...) such as someone claiming to have an 86-bit PC running Windows 2000 (I guess they meant 32-bit x86 ) and another person posted something so off, I'm inclined to think it was fail trolling (claimed to remove the PSU and GPU and boot the machine just fine; yeah, obviously absurd )
Also, x64 CPUs do not always (often they don't, especially for home markets...) have 64-bit memory addressing...
My Computer
Computer Manufacturer/Model Number
iBuyPower Chimera X58
OS
Windows 8 Pro x64
CPU
Intel Core i7 920
Motherboard
Asus P6T Deluxe V2
Memory
12GB (2GB x6) Triple Channel DDR3 1333 MHz
Graphics Card(s)
ATI Radeon HD 4870 X2 2GB GDDR5
Sound Card
Integrated Digital HD 7.1 Surround Sound
Monitor(s) Displays
24.6-inch ASUS VW246H 20000:1 Contrast, 2 ms response time,