Windows not detecting USB mouse at startup

I apologise about the content here. I am having 3 separate issues although the one mentioned in the title is most important. I just managed to put this build together yesterday, with the help of a friend. My first build ever. Powered up first time, no major issues, just a few questions:

1) I am using a razer mouse (ive installed its driver/Razer Synapse) and for some reason my computer doesnt pick it up upon startup, i have to plug it out and in each time for it to work. Ive installed the msi driver that came with the mobo. I ran the 200+ windows update but had to call it an early night because work next morning. I asked my friend and he said he had the same issue with his build, and it was something in the bios but he cant remember properly. Im going to try installing intel usb 3.0 driver i found on msi's website. Im pretty sure it was included in the list of drivers from the mobo but there must be a reason why this is available to download separately on their website. This issue is only caused by the mouse, tried all usb ports, keyboard and other mice work fine. Once plugged in, it doesnt even say installing new driver it just works instantaneously.

2) Mobo came with Sound Blaster Cinema 2 as well as Realtek HD Audio. I can guess sound blaster would be the superior one out of the two so shall i simply uninstall realtek? They are both installed at the moment but I'm not sure which is active/more dominant (if it even works like that). The problem I'm having is all music and sound effects are incredibly loud, voice/dialogue is really quiet. Not just in movies but games, videos, pretty much anything.

3) My gpu ram is 6gb ram, dxdiag only shows ~1.3gb. Normal ram is 8gb, dxdiag only shows less than 3. But CPU-ID shows everything correctly. I vaguely remember a reddit post a few days/weeks ago regarding the rams being limited due to some setting in the bios. Is it actually being limited?

**Update:**

1) so I installed the intel usb 3.0 driver from msi's website, made no difference. Uninstalled and reinstalled razer drivers, no success. Turned off usb legacy support at bios (previously was on), no difference. Change energy settings to high performance, no difference. I noticed that my mobo has this click bios feature. The mouse works properly in the bios, only once windows start it doesnt work until i plug it in again.