8 card chinese rig crashes when OC

hello,

i just received those chinese rigs with the 65mm 8 slot b75 motherboards, i plugged 8 cards in and everything is fine, up until i OC over 2100mhs the motherboard cant handle it and it freezes and resets. on the bios i have above 4g decoding enabled with intergrated graphics disabled. it seems like the pcie slots cant handle the traffic? i’ve gone through a lot of settings on the bios and cant figure it out.

any help would be greatly appreciated!