Inspiron 3847: Advanced bios settings

Hello.

I would like to use two dvb cards in my inspiron 3847, but the cards aren't recognized.

Bios is up to date (A07), pcie slots are ok (with other cards), cards are ok (on other computers). The support of the card manufacturer told me to set the pcie slots to gen1 in bios, but this option isn't available. Are there hidden settings somewhere or is it possible to use another bios version with more settings?

Thanks