Computer/soundcard boot problems after upgrading graphicscard GTX 960

I have 2 problems after upgrading Gtx 560 150W to MSI GTX 960 2gb 120 W
- computer starts slower and a weird screen, cant enter BIOS
- computer does not recognize pci soundcard (ASUS XONAR DX), not listed in device manager, also not under unidentified devices.

I have been looking for solutions the whole week and I thought i should post a thread.

what I have tried:
- reinstalling windows
- windows recovery, all options.
- check if everything is properly connected.
- trying to get in bios with a PS2 keyboard
- memory remove and reinstall
- removing soundcard and reinstall
- looking for drivers --> asks me to connect audio card
- connect the old graphics card --> it solved the boot problem, the computer started fast again with the bios screen (picture 1) only lasting about 3 sec. I could enter bios again and I resetted bios. however the soundcard is still not showning up. after installing the gtx 960 again same problem with booting.

I didnt try to reset CMOS because i could enter bios when i connected with the 560 graphics card.
I dont want to accidently brick my computer.
I only have one accessible pci slot for the soundcard so i cant switch to other pci port.

the pictures when booting with gtx 960 installed
picture 1 lasts about 2-3 minutes with about 5 beeps with a lot of time between them.
https://www.dropbox.com/s/s29hxf8ggt...82%29.jpg?dl=0

picture 2 lasting about 3 sec.
https://www.dropbox.com/s/jxtccb21xz...G0714.jpg?dl=0

when I am in windows the graphics card works just fine.
I think these 2 problems are related. and if the boot problem is solved the soundcard might be solved 2.

I am looking forward for ur suggestions, thanks in advance.

thanks for ur reply
Dc output - 450 W
The max Watt used should be less because I installed a graphicscard that has 30 W less TDP
before the install the soundcard and everything else worked just fine.
The beeps have about 20-30 sec time between them.
I will try to disconnect my HDD and CD-drive temporarily so the system has more Power left.

Disconnecting the harddrive and CD drive had no effect.
I have looked through the manual and there are no beep codes listed.
I found a site with codes: Computer POST and beep codes
the first beep at start up has a slightly different sound than the ones following.
I think this beep says that the system is fine. i cant find my code in the Post codes list.

I had disconnected both hdd nd ssd so it couldnt boot in wndows.
becuse the drivers are installed on the ssd and the first screen staays ecactly the same. does this mean that its not a driver problem?

picture of PSU sticker
https://www.dropbox.com/s/7mvxfudxr5...G0720.jpg?dl=0

i Have found a thread on another forum with the same motherboard and a gtx 770 and the same problem
PC takes ages to boot after new GTX 770 (Stuck on BIOS) [Solved] - BIOS - Motherboards

He had fixed it with flashing his bios. I am going to try this.

I have downloaded the bios driver from the manufacturers site.
but it says "ROM file does not match existing bios size"

someone got a solution to solve this?

Yes I am,
Detection software:
https://www.dropbox.com/s/cl2usttwuc...mloos.jpg?dl=0
site i downloaded it from
www.medion.com/nl/service/_lightbox/treiber_details.php?did=10128

Is it possible the manufacturer modified something so the bios images dont match in size?