Does anyone have an idea what can lead to this hashrate?

All chips seem to be fine. It is powered by a 1600W PSU (all 4 PCIe Cables connected), but it is only ~half of the promised hashrate.
Latest firmware is also installed...
Kind regards
what does your pool say you are mining at?
I have had bizzare reading in the gui that do not match my pool's numbers. In the end the pool pays you not the gui .
is cex.io reading 250gh?