To add more information to this problem, I tried reverting to an older kernel, no changes, errors still occur at exactly the same point.
I have not had time to try this yet due to work, but I am going to put my old card in and see if the same issue occurs with a different card, hopefully eliminating a problem with the card as a possible source of the problem.
I have had various errors come and go through trying various things to get this to work, however, the following is the errors from the X log file that occurs every time:
[212711.480] (EE)
[212711.480] (EE) Backtrace:
[212711.480] (EE) 0: /usr/bin/X (xorg_backtrace+0x3d) [0x7f357a40102d]
[212711.480] (EE) 1: /usr/bin/X (0x7f357a25f000+0x1a5d99) [0x7f357a404d99]
[212711.480] (EE) 2: /lib/x86_64-linux-gnu/libpthread.so.0 (0x7f357935f000+0xfbb0) [0x7f357936ebb0]
[212711.480] (EE) 3: /usr/bin/X (doListFontsWithInfo+0x179) [0x7f357a2b4a59]
[212711.481] (EE) 4: /usr/bin/X (ProcessWorkQueue+0x21) [0x7f357a2b8521]
[212711.481] (EE) 5: /usr/bin/X (WaitForSomething+0x79) [0x7f357a3fe4c9]
[212711.481] (EE) 6: /usr/bin/X (0x7f357a25f000+0x54d61) [0x7f357a2b3d61]
[212711.481] (EE) 7: /usr/bin/X (0x7f357a25f000+0x4456a) [0x7f357a2a356a]
[212711.481] (EE) 8: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf5) [0x7f3577f9ade5]
[212711.481] (EE) 9: /usr/bin/X (0x7f357a25f000+0x448af) [0x7f357a2a38af]
[212711.481] (EE)
[212711.481] (EE) Segmentation fault at address 0x7f6f1a7ab0f0
[212711.481] (EE)
Fatal server error:
[212711.481] (EE) Caught signal 11 (Segmentation fault). Server aborting
[212711.481] (EE)
[212711.481] (EE)
Please consult the The X.Org Foundation support
at http://wiki.x.org
for help.
[212711.481] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[212711.481] (EE)
[212711.662] (EE) Server terminated with error (1). Closing log file.
I have tried searching the web for errors relating to libpthread and libc which are both part of the same Ubuntu package, but have not found anything relevant. The package is the stock version (2.17) that was installed with Ubuntu, has never been upgraded nor is the an update available for it at this time.