After Windows 10 updated itself to version 1607, my Boinc no longer runs GPU dependant tasks.
I checked I have the latest NVIDIA drivers and uninstalled and reinstalled BOINC, to no avail.
Help/suggestions appreciated.
Event log attached :-

07/02/2017 21:40:11 |  | Starting BOINC client version 7.6.33 for windows_x86_64
07/02/2017 21:40:11 |  | log flags: file_xfer, sched_ops, task
07/02/2017 21:40:11 |  | Libraries: libcurl/7.47.1 OpenSSL/1.0.2g zlib/1.2.8
07/02/2017 21:40:11 |  | Data directory: C:\ProgramData\BOINC
07/02/2017 21:40:11 |  | Running under account Dave
07/02/2017 21:40:12 |  | CUDA: NVIDIA GPU 0: GeForce GTX 1080 (driver version 378.49, CUDA version 8.0, compute capability 6.1, 4096MB, 3557MB available, 8876 GFLOPS peak)
07/02/2017 21:40:12 |  | App version needs OpenCL but GPU doesn't support it
07/02/2017 21:40:12 | Collatz Conjecture | Application uses missing NVIDIA GPU
07/02/2017 21:40:12 |  | App version needs OpenCL but GPU doesn't support it
07/02/2017 21:40:12 | Collatz Conjecture | Application uses missing NVIDIA GPU
07/02/2017 21:40:12 |  | app version refers to missing GPU type ATI
07/02/2017 21:40:12 | Milkyway@Home | Application uses missing ATI GPU
07/02/2017 21:40:12 |  | app version refers to missing GPU type ATI
07/02/2017 21:40:12 | Milkyway@Home | Application uses missing ATI GPU
07/02/2017 21:40:12 |  | app version refers to missing GPU type ATI
07/02/2017 21:40:12 | Milkyway@Home | Application uses missing ATI GPU
07/02/2017 21:40:12 |  | App version needs OpenCL but GPU doesn't support it
07/02/2017 21:40:12 | Milkyway@Home | Application uses missing NVIDIA GPU
07/02/2017 21:40:12 |  | App version needs OpenCL but GPU doesn't support it
07/02/2017 21:40:12 | Milkyway@Home | Application uses missing NVIDIA GPU
07/02/2017 21:40:12 |  | App version needs OpenCL but GPU doesn't support it
07/02/2017 21:40:12 | Milkyway@Home | Application uses missing NVIDIA GPU
07/02/2017 21:40:12 |  | app version refers to missing GPU type ATI
07/02/2017 21:40:12 | PrimeGrid | Application uses missing ATI GPU
07/02/2017 21:40:12 |  | app version refers to missing GPU type ATI
07/02/2017 21:40:12 | SETI@home | Application uses missing ATI GPU
07/02/2017 21:40:12 |  | app version refers to missing GPU type ATI
07/02/2017 21:40:12 | SETI@home | Application uses missing ATI GPU
07/02/2017 21:40:12 |  | Host name: Xclio-A380
07/02/2017 21:40:12 |  | Processor: 20 GenuineIntel Intel(R) Core(TM) i7-6950X CPU @ 3.00GHz [Family 6 Model 79 Stepping 1]
07/02/2017 21:40:12 |  | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss htt tm pni ssse3 fma cx16 sse4_1 sse4_2 movebe popcnt aes f16c rdrandsyscall nx lm avx avx2 vmx tm2 dca pbe fsgsbase bmi1 hle smep bmi2
07/02/2017 21:40:12 |  | OS: Microsoft Windows 10: Professional x64 Edition, (10.00.14393.00)
07/02/2017 21:40:12 |  | Memory: 63.91 GB physical, 64.11 GB virtual
07/02/2017 21:40:12 |  | Disk: 476.38 GB total, 119.23 GB free
07/02/2017 21:40:12 |  | Local time is UTC +0 hours
07/02/2017 21:40:12 |  | VirtualBox version: 5.1.10
07/02/2017 21:40:12 | ATLAS@home | Found app_config.xml
07/02/2017 21:40:12 | ATLAS@home | Your app_config.xml file refers to an unknown application 'ATLAS_MCORE'.  Known applications: None
07/02/2017 21:40:12 |  | Config: don't use GPUs while EDLaunch.exe is running
07/02/2017 21:40:12 |  | Config: don't use GPUs while PinnacleStudio.EXE is running
07/02/2017 21:40:12 | Asteroids@home | URL http://asteroidsathome.net/boinc/; Computer ID 262374; resource share 100
07/02/2017 21:40:12 | ATLAS@home | URL http://atlasathome.cern.ch/; Computer ID 50207; resource share 100
07/02/2017 21:40:12 | climateprediction.net | URL http://climateprediction.net/; Computer ID 1232922; resource share 100
07/02/2017 21:40:12 | Collatz Conjecture | URL https://boinc.thesonntags.com/collatz/; Computer ID 650530; resource share 100
07/02/2017 21:40:12 | Constellation | URL http://aerospaceresearch.net/constellation/; Computer ID 6680; resource share 100
07/02/2017 21:40:12 | GPUGRID | URL http://www.gpugrid.net/; Computer ID 119693; resource share 100
07/02/2017 21:40:12 | LHC@home | URL https://lhcathome.cern.ch/lhcathome/; Computer ID 10369940; resource share 100
07/02/2017 21:40:12 | malariacontrol.net | URL http://www.malariacontrol.net/; Computer ID 463320; resource share 100
07/02/2017 21:40:12 | Milkyway@Home | URL http://milkyway.cs.rpi.edu/milkyway/; Computer ID 358928; resource share 100
07/02/2017 21:40:12 | MindModeling@Beta | URL http://mindmodeling.org/; Computer ID 73778; resource share 100
07/02/2017 21:40:12 | NFS@Home | URL http://escatter11.fullerton.edu/nfs/; Computer ID 2240544; resource share 100
07/02/2017 21:40:12 | PrimeGrid | URL http://www.primegrid.com/; Computer ID 234139; resource share 100
07/02/2017 21:40:12 | rosetta@home | URL http://boinc.bakerlab.org/rosetta/; Computer ID 1559989; resource share 100
07/02/2017 21:40:12 | SETI@home | URL http://setiathome.berkeley.edu/; Computer ID 7625220; resource share 100
07/02/2017 21:40:12 | VirtualLHC@home | URL http://lhcathome2.cern.ch/vLHCathome/; Computer ID 98465; resource share 100
07/02/2017 21:40:12 | wanless2 | URL http://bearnol.is-a-geek.com/wanless2/; Computer ID 28477; resource share 100
07/02/2017 21:40:12 | World Community Grid | URL http://www.worldcommunitygrid.org/; Computer ID 3576620; resource share 50
07/02/2017 21:40:12 | WUProp@Home | URL http://wuprop.boinc-af.org/; Computer ID 100824; resource share 100
07/02/2017 21:40:12 | yafu | URL http://yafu.myfirewall.org/yafu/; Computer ID 11766; resource share 100
07/02/2017 21:40:12 | World Community Grid | General prefs: from World Community Grid (last modified 31-Jan-2017 17:50:47)
07/02/2017 21:40:12 | World Community Grid | Computer location: home
07/02/2017 21:40:12 |  | General prefs: using separate prefs for home
07/02/2017 21:40:12 |  | Reading preferences override file
07/02/2017 21:40:12 |  | Preferences:
07/02/2017 21:40:12 |  | max memory usage when active: 49083.01MB
07/02/2017 21:40:12 |  | max memory usage when idle: 58899.61MB
07/02/2017 21:40:12 |  | max disk usage: 20.00GB
07/02/2017 21:40:12 |  | max CPUs used: 5
07/02/2017 21:40:12 |  | (to change preferences, visit a project web site or select Preferences in the Manager)
07/02/2017 21:40:13 | Constellation | Fetching scheduler list
07/02/2017 21:40:14 | Constellation | [error] No scheduler URLs found in master file
07/02/2017 21:40:19 | Milkyway@Home | Sending scheduler request: To fetch work.
07/02/2017 21:40:19 | Milkyway@Home | Requesting new tasks for NVIDIA GPU
07/02/2017 21:40:22 | Milkyway@Home | Scheduler request completed: got 0 new tasks
07/02/2017 21:40:27 | Collatz Conjecture | Sending scheduler request: To fetch work.
07/02/2017 21:40:27 | Collatz Conjecture | Requesting new tasks for NVIDIA GPU
07/02/2017 21:40:28 | Collatz Conjecture | Scheduler request completed: got 0 new tasks

After Windows 10 updated itself to version 1607, my Boinc no longer runs GPU dependant tasks.
I checked I have the latest NVIDIA drivers and uninstalled and reinstalled BOINC, to no avail.

You're using Windows installed drivers, these lack OpenCL. You need to install the GPU drivers from the Nvidia website: http://www.nvidia.com/Download/index.aspx?lang=en-us

Also set Windows not to update the drivers, as else it'll dump ones on you again without the needed OpenCL.
And each time in the future that Windows updates itself do you need to install drivers from the Nvidia website.

You can clean install the drivers from the installer. There's an option for that someplace in the installer, so read each window intricately.

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Thanks Ageless - I'm starting to hate Windows 10 updates, there's always something that gets screwed up. :-(