Re: GT 520 PCI reports 1024 instead of 512
The incorrect memory size reporting is probably unrelated to the crashes you are seeing. Can you please run an OpenGL application through gdb, reproduce the crash, and then attach the output of "info registers", "info files", "backtrace", and "disassemble $pc-50,$pc+50"?
Also, there are a few, "GPU at 0000:04:00.0 has fallen off the bus," errors in your system log. This indicates a system-level problem that could be caused by physical problems. Please make sure the board is firmly seated in the motherboard and that the fan and heatsink are clean.