All important information should by in logs below,.. so just quick:
OS:Linux (Archlinux)
SW: Boinc from official arch comunity repo, Catalyst (15.12-1) from Vi0L0 repo, Xorg Server (1.17.4-2) from Vi0L0 repo
HW: AMD Radeon HD 7770

Problem: When i start Boinc Manager i get message in log

Tue 05 Apr 2016 08:44:45 PM CEST |  | No usable GPUs found

in case i try to start client simply from command line

etnyx@etnyx-work ~ % boinc_client
05-Apr-2016 20:57:01 [---] cc_config.xml not found - using defaults
05-Apr-2016 20:57:30 [---] Starting BOINC client version 7.6.31 for x86_64-pc-linux-gnu
05-Apr-2016 20:57:30 [---] log flags: file_xfer, sched_ops, task
05-Apr-2016 20:57:30 [---] Libraries: libcurl/7.48.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 libssh2/1.7.0
05-Apr-2016 20:57:30 [---] Data directory: /home/etnyx
execv: No such file or directory
05-Apr-2016 20:57:30 [---] GPU detection failed. error code 512
05-Apr-2016 20:57:30 [---] No usable GPUs found
05-Apr-2016 20:57:30 [---] Host name: etnyx-work
05-Apr-2016 20:57:30 [---] Processor: 3 AuthenticAMD AMD Athlon(tm) II X3 445 Processor [Family 16 Model 5 Stepping 3]
05-Apr-2016 20:57:30 [---] Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nopl non
stop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefe
tch osvw ibs skinit wdt hw_pstate npt lbrv svm_lock nrip_save vmmcall
05-Apr-2016 20:57:30 [---] OS: Linux: 4.1.20-1-lts
05-Apr-2016 20:57:30 [---] Memory: 7.80 GB physical, 5.40 GB virtual
05-Apr-2016 20:57:30 [---] Disk: 292.50 GB total, 43.00 GB free
05-Apr-2016 20:57:30 [---] Local time is UTC +2 hours
05-Apr-2016 20:57:30 [---] No general preferences found - using defaults
05-Apr-2016 20:57:30 [---] Preferences:
05-Apr-2016 20:57:30 [---]    max memory usage when active: 3993.39MB
05-Apr-2016 20:57:30 [---]    max memory usage when idle: 7188.10MB
05-Apr-2016 20:57:30 [---]    max disk usage: 49.08GB
05-Apr-2016 20:57:30 [---]    don't use GPU while active
05-Apr-2016 20:57:30 [---]    suspend work if non-BOINC CPU load exceeds 25%
05-Apr-2016 20:57:30 [---]    (to change preferences, visit a project web site or select Preferences in the Manager)

and now for me strange part, command boinc_client should be shortcut for full path of command so

etnyx@etnyx-work ~ % which boinc_client
/usr/bin/boinc_client
etnyx@etnyx-work ~ % /usr/bin/boinc_client
05-Apr-2016 21:30:57 [---] cc_config.xml not found - using defaults
05-Apr-2016 21:31:27 [---] Starting BOINC client version 7.6.31 for x86_64-pc-linux-gnu
05-Apr-2016 21:31:27 [---] log flags: file_xfer, sched_ops, task
05-Apr-2016 21:31:27 [---] Libraries: libcurl/7.48.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 libssh2/1.7.0
05-Apr-2016 21:31:27 [---] Data directory: /home/etnyx
05-Apr-2016 21:31:27 [---] CAL: ATI GPU 0: AMD Radeon HD 7700/R7 250X/R9 255 series (Capeverde) (CAL version 1.4.1848, 1024MB, 528MB available, 3520 GFLOPS peak)
05-Apr-2016 21:31:27 [---] OpenCL: AMD/ATI GPU 0: AMD Radeon HD 7700/R7 250X/R9 255 series (Capeverde) (driver version 1912.5 (VM), device version OpenCL 1.2 AMD-APP (1912.5), 1024MB, 528MB available, 3520 GFLOPS peak)
05-Apr-2016 21:31:27 [---] Host name: etnyx-work
05-Apr-2016 21:31:27 [---] Processor: 3 AuthenticAMD AMD Athlon(tm) II X3 445 Processor [Family 16 Model 5 Stepping 3]
05-Apr-2016 21:31:27 [---] Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nopl nonstop_tsc extd_apicid pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt hw_pstate npt lbrv svm_lock nrip_save vmmcall
05-Apr-2016 21:31:27 [---] OS: Linux: 4.1.20-1-lts
05-Apr-2016 21:31:27 [---] Memory: 7.80 GB physical, 5.40 GB virtual
05-Apr-2016 21:31:27 [---] Disk: 292.50 GB total, 43.00 GB free
05-Apr-2016 21:31:27 [---] Local time is UTC +2 hours
05-Apr-2016 21:31:27 [---] No general preferences found - using defaults
05-Apr-2016 21:31:27 [---] Preferences:
05-Apr-2016 21:31:27 [---]    max memory usage when active: 3993.39MB
05-Apr-2016 21:31:27 [---]    max memory usage when idle: 7188.10MB
05-Apr-2016 21:31:27 [---]    max disk usage: 49.09GB
05-Apr-2016 21:31:27 [---]    don't use GPU while active
05-Apr-2016 21:31:27 [---]    suspend work if non-BOINC CPU load exceeds 25%
05-Apr-2016 21:31:27 [---]    (to change preferences, visit a project web site or select Preferences in the Manager)

And now GPU is detected, Should someone point some direction how to fix this, how to use GPU in boinc manager?

There is also very simillar thread in this board (but locked) and no solution: https://boinc.berkeley.edu/dev/forum_thread.php?id=9907#59402[/quote][/code]

Generally, this indicates a timing problem during start up.

Once you have booted and have the message no usable gpu, you need to restart boinc using boinc-client restart

---

When life hands you lemons, stick some nails in them and wire them up to power a DC rig.

Hi - i can't say i have experience with boinc on Archlinux but there are some instructions here

Was this the route you took to install?

A quick recap on how the ArchLinux package is set up would be nice. As in, is BOINC set up as a service that starts up automatically when the system boots, where's the data directory and such.

Assuming the package sets up BOINC as service. As Rudy said this could be a matter of BOINC starting before GPU drivers are loaded. It's also possible that you need allow BOINC client to access the X server. You can run the command "xhost +SI:localuser:boinc" in terminal or add the command somewhere in X startup scripts. In both cases you need to restart the service after X is started.

edit: AgentB thanks for digging up the ArchLinux page. Which umm... says pretty much the same as I said above... :edit

When starting BOINC client it is necessary to use path to the client executable for GPU detection to work. Fixing this is on the todo list.

At first thx for your response.

Rudy Toody: As I believe Im using Arch in "Arch way", so im not starting boinc at boot sequence but on demand by my hands,.. Xorg server and Catalyst are fully loaded at this time.

Agentb: thx i didint notice this page, my installation process was very simillar to this, except adding boinc into video group. Since there is systemd, this group should by obsolated. Anyway i try it but it didnt fix it :-(

Juha: something i explane above,.. about Arch package, I believe my tech skills are not enought to provide all info you need.

But i made some progress, I didnt start any GPU computation yet but im able to detec GPU now in manager.

My how to:

1) sudo xhost +SI:localuser:boinc
2) sudo systemctl restart boinc.service
3.1) /usr/bin/boinc_client
3.2) start boincmgr

3.1, 3.2 in rapid succession
in case i didnt run 3.1 boinc manager use Data Directory at /var/lib/boinc and dont detect GPU
in case i run 3.1 boinc manager use Data Direcotry at ~/ and detect GPU

I will keep diging,...


EDIT: now im able to run PG tasks atiGNF16