GPU tweak is crashing for me too. Asus z97a, two strix 970s, fresh install of windows 8.1 and latest nvidia drivers...
Faulting application name: Monitor.exe, version: 1.4.0.1, time stamp: 0x54f94b65
Faulting module name: nvapi.dll, version: 9.18.13.5306, time stamp: 0x5566817b
Exception code: 0xc0000094
Fault offset: 0x001f4d14
Faulting process id: 0x1138
Faulting application start time: 0x01d0ac3e21ad5bd4
Faulting application path: C:\Program Files (x86)\ASUS\GPU Tweak\Monitor.exe
Faulting module path: C:\Windows\system32\nvapi.dll
Report Id: ba7f991b-1831-11e5-825d-1c872c712905
Faulting package full name:
Faulting package-relative application ID:
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Faulting application name: ASUSxGPU-Z.exe, version: 1.0.5.3, time stamp: 0x54b27303
Faulting module name: ASUSxGPU-Z.exe, version: 1.0.5.3, time stamp: 0x54b27303
Exception code: 0xc0000005
Fault offset: 0x0011446f
Faulting process id: 0xa70
Faulting application start time: 0x01d0ac3fa48af502
Faulting application path: C:\Program Files (x86)\ASUS\GPU Tweak\ASUSxGPU-Z.exe
Faulting module path: C:\Program Files (x86)\ASUS\GPU Tweak\ASUSxGPU-Z.exe
Report Id: e37b820c-1832-11e5-825d-1c872c712905
Faulting package full name:
Faulting package-relative application ID: