I'm quite new to Final Fantasy XIV and have more or less the same Problem, i start ffxivboot.exe turn on DX11 then i fill in my user id and password click on start and get an APPCRASH:

Problemsignatur:
Problemereignisname: APPCRASH
Anwendungsname: ffxiv_dx11.exe
Anwendungsversion: 1.0.0.0
Anwendungszeitstempel: 558e0e6d
Fehlermodulname: ffxiv_dx11.exe
Fehlermodulversion: 1.0.0.0
Fehlermodulzeitstempel: 558e0e6d
Ausnahmecode: c0000005
Ausnahmeoffset: 00000000000089d4
Betriebsystemversion: 6.3.9600.2.0.0.256.4
Gebietsschema-ID: 1031
Zusatzinformation 1: 5696
Zusatzinformation 2: 569669062c115b0629f04d1397c4549f
Zusatzinformation 3: 4bad
Zusatzinformation 4: 4badcb915d96381d49255a3ee3e66917

and this is the sysinfo from ffxivsysinfo.exe:


-=-=-=-=-=-=- FFXIV Information -=-=-=-=-=-=-

MyDocument C:\Users\blaH\Documents
FINAL FANTASY XIV - A Realm Reborn Language 1 Region 3
ProxyEnable 0
ProxyServer unspecified
ProxyOverride unspecified


-=-=-=-=-=-=- System Information -=-=-=-=-=-=-

SYSTEM_OS Windows 8.1 Enterprise 64-Bit-Version (6.2, Build 9200) (9600.winblue_r9.150322-1500)
SYSTEM_CPU Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz (8 CPUs), ~3.5GHz
SYSTEM_CORE_NUM SYSTEM_CORE_LOGIC 8 SYSTEM_CORE_PHYSICS 4
SYSTEM_BIOS BIOS Date: 06/01/15 15:05:52 Ver: 04.06.05
SYSTEM_LANGUAGE Deutsch (Gebietsschema: Deutsch)
SYSTEM_MEMORY 8143.125MB
SYSTEM_VIRTUAL_MEMORY 2047.875MB
SYSTEM_PAGE_FILE 9423.125MB
SYSTEM_STORAGE C:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 148.702GB SYSTEM_FREEDISC_SPACE 32.874GB
SYSTEM_STORAGE S:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 149.047GB SYSTEM_FREEDISC_SPACE 82.624GB
SYSTEM_STORAGE X:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 2794.512GB SYSTEM_FREEDISC_SPACE 1286.517GB
SYSTEM_STORAGE Y:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 931.511GB SYSTEM_FREEDISC_SPACE 43.895GB
SYSTEM_STORAGE Z:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 931.511GB SYSTEM_FREEDISC_SPACE 50.813GB
SYSTEM_DIRECTX_VERSION DirectX 11
SYSTEM_GRAPHICS NVIDIA GeForce GTX 560 Ti
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY7
SYSTEM_GRAPHICS_CHIP GeForce GTX 560 Ti
SYSTEM_GRAPHICS_MAKER NVIDIA
SYSTEM_GRAPHICS_VRAM 973.434 MB
SYSTEM_GRAPHICS_SHARED_VRAM 3071.887 MB
SYSTEM_GRAPHICS_DAC Integrated RAMDAC
SYSTEM_GRAPHICS_DISPLAY_MODE 1920 x 1080 (32 bit) (60Hz)
SYSTEM_GRAPHICS_DRIVER nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
SYSTEM_GRAPHICS_DRIVER_VERSION 10.18.0013.5330
SYSTEM_GRAPHICS_DRIVER_DATE 17.06.2015 11:10:27
SYSTEM_GRAPHICS_DRIVER_LANGUAGE Englisch
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_SOUND Lautsprecher (ASUS Xonar Essence STX Audio Device)
SYSTEM_SOUND_DEVICE_ID {AC77FD39-E519-46D3-AD1B-8E6E95A038DB}
SYSTEM_SOUND_DEVICE_NAME cmudaxp.sys
SYSTEM_SOUND_DRIVER_VERSION 5.12.0001.0008
SYSTEM_SOUND_DRIVER_LANGUAGE Englisch
SYSTEM_SOUND_DRIVER_DATE 11.12.2013 11:09:46
SYSTEM_INPUT {6F1D2B60-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Maus
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 3 SYSTEM_GAMEPAD_BUTTON 8 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {6F1D2B61-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Tastatur
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 128 SYSTEM_GAMEPAD_FOV 0


-=-=-=-=-=-=- Application Information -=-=-=-=-=-=-

boot
dx11 crashing? - Page 5 - Pale Moon
.
.
.
-=-=-=-=-=-=- Proccess Information -=-=-=-=-=-=-

C:\Windows\SysWOW64\rundll32.exe 00000EDC
X:\FINAL FANTASY XIV - A Realm Reborn\boot\ffxivsysinfo.exe 00000A7C

the funny thing is, sometimes it works... but yeah most of the Time not