5700 XT + 2x 6700XT unstable

Hi, have this settings and system is very unstable… Bad OC?
All 3 card are without BIOSMOD.

Hello

For Rx 6700
|Core:|1250|
|Memory Mhz:|1075|
|Core undervolt:|675|
|MVDD:|1300|
|MVDDCI:|800|

For Rx5700 (lower your mvdd 850 ) u are ok because u are in stock bios…