But its normal when the gpu its pluged to frezze the whole rig?
An important rule of any miner is not to repair the video card on a working mining farm. To do this, you need to use a separate computer with a built-in video card, so as not to flash the BIOS of another video card by mistake.
If you do not want to follow this rule, then during the experiments, disconnect the working video cards, and if the motherboard does not have integrated graphics, then use any GPU, such as GT 210.