We can see that your system is using 266.66 and as you described.

The symptoms (1% utilization) can be caused by a number of things:
Settings that prevent the use of the GPU when the user is active, non-Boinc programs using too much of the system resources along with undesirable Boinc settings, the task being suspended, Snooze being used, not using recommended settings (the CPU not being available)...

1% load is about right for background GPU use only (monitor displaying a basic web page) - i.e. no crunching or heavy GPU use.
Check your computing preferences in Boinc (Processor usage).

I can see you are not using the recommended settings, and contribute to 4 CPU projects. So my guess is that these other processes are hogging the CPU and starving the GPU. The heavier I/O projects can exasperate such problems.
Configure Boinc to crunch with 7 CPU threads and use swan_sync. You may be experiencing other problems, downclocking, low power mode, or some of the above as well, but this should make the picture clearer.

FAQ: Best configurations for GPUGRID

Have you configured Boinc to use 7 CPU cores?
This is required along with swan_sync.

We have always needed to disable a CPU core/thread to guarantee that it's free for the GPU to utilize when it needs to. If we do not then it's down to the tasks you crunch, but could be influenced by system updates, drivers and obviously application changes. By default GPU tasks are run at a slightly higher priority than CPU tasks, but that does not mean they will immediately get access to the CPU and some CPU projects might not stick to this. With HT CPU's I would expect trying to use all 8 threads would lead to more noticeable GPU downtime; there is always a backlog.
On the upside leaving one CPU core free greatly improves the performance of the GPU tasks, reduces failures, tends to improve system responsiveness, reduces the CPU Time to Elapsed Time delta for CPU tasks, and on HT systems you are really only losing half a core.