Laptop noisy (used to be fixed by vgaswitcheroo)

My Sony Vaio laptop with a discrete Radeon (TURKS) graphics card has an annoying hum noise. This used to be fixed in a previous version of Ubuntu by using vgaswitcheroo to switch the discrete card off, but this no longer works. I have also tried acpi call GUI, but there is no deactivation code for my laptop.

Does anyone know how to fix this or how and whether it would be possible to look at getting vgaswitcheroo working again for my system?

Vaio Model: VPCCA15FG

$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6630M/6650M/6750M/7670M/7690M] (rev ff)

$ sudo cat /sys/kernel/debug/vgaswitcheroo/switch
0:DIS: :DynOff:0000:01:00.0
1:IGD:+:Pwr:0000:00:02.0

Using Ubuntu 15.10 and also recently installed Ubuntu 16.04 as well which I have the feeling has a slightly worse hum, but could be my imagination.