fglrx - AMD Radeon HD 5650M

Ok, so I've got the 5650 as a discrete gpu and integrated 4200. The problem is that I cant switch to 5650.
fglrxinfo shows that 4200 is on, but aticonfig -px-list shows that Discrete GPU is active.

lspci shows this:

01:05.0 VGA compatible controller [0300]: ATI Technologies Inc M880G [Mobility Radeon HD 4200] [1002:9712]

02:00.0 VGA compatible controller [0300]: ATI Technologies Inc Madison [AMD Radeon HD 5000M Series] [1002:68c1] (rev ff)

as xorg looks like this:

xorg device section:

Section "Device"

Identifier "aticonfig-Device[0]-0"

Driver "fglrx"

BusID "PCI:1:5:0"

EndSection

I thought that if I change busid to PCI:2:0:0 it'll help, but it won't.
looks like ubuntu can't see 5650 as with PCI:2:0:0 I cant run X.
any suggestions what to do?

Also I can't disable 4200 in BIOS

Have you tried switching with vgaswitcheroo? For more information on this topic, have a look at HybridGraphics in Ubuntu.
When it comes to owning vgaswitcheroo, I use:

sudo chmod -R 705 /sys/kernel/debug and

sudo chown -R $YOURUSERNAME:$YOURUSERNAME /sys/kernel/debug/vgaswitcheroo

I don't use the proprietary drivers though.