I have Sapphire pulse rx 5700 xt.. I've just bought it today and made a clean install with drivers.. My old rx 480 was running on full gpu clock speed but this one is fluctating.. and thats causes my games to stutter.. I supposed to take like 110-120 fps on gta 5 ( 1080 p ultra) but because of this fluctating, i cant take it. 30 fps, 40 fps is highest in my game. Sometimes it hits 60 fps but instantly go down..
My core clock needs to work at 1800+ mhz and this fluctating made them like 1000-900- 1200 mhz..