xps 9550 issues

There is a list of issue i've got with my computer.

Dell technical support so far has been completely useless. (hours of Calls, remote access, went to the store).

All drivers are updated to the latest version.

Main issues:
- Sleep of Death. Does not wake from sleep - the computer seems to starts, hangs on a black screen for a while and then reboot. -> en.community.dell.com/.../19586456
- The computer goes into some state that the screen is black, the computer is running and there is nothing else but holding the power button down to restart it.
- Display driver not responsive and has recovered.
- Getting BSOD 4-5 times a week, sometimes 3-4 times a day.
- The computer is not able to wake the external monitor from sleep. This monitor is working fine with a lenovo laptop. I've tried HDMI, DP, Thourgh TB15 dock, nothing works. Has to unplug replug the cable. The computer does wake when the computer boot.
- The speaker does not work properly, sound is very bad and buzzing.
- repeated explorer crashes and freezes, the windows startup bar freezes or is slow to respond
- HDMI is not able to drive a screen 2560x440 more than 23Hz. Macbook pro works without any problem on the same screen using the same cable.

TB15 Dock:
Never been able to make it work properly.
- Sometimes the dock crashes, need to disconnect everything and reconnect, including power cable.
- Sometimes the dock reset during use, which can be extremely annoying. The change of screen to high DPI makes several software crash and cause loss of work.