ok i think this is the topic i was looking for .
I have 4 RX 480 nitro+ 8gb , an old mobo with 4 pci slots , 4 pci risers and 1200w corsair 1200i PSU. i am already trying to mod bios for a week now , modding itself is easy but getting the rig rock stable does not work for me ...

my resultas so far :

started out with base bios and base settings , so i get 640 hash per card so 2550 all together , runs stable for 15 hours ( did not test it longer but it looks really stable ).
then i tried 1500 straps , 1625 straps and last 1750 straps ( seem to be the best for rx480 with samsung memory ). But when was mining with all of these straps in all 4 cards
with basic settings , the rig does only run for a couple of hours. with the 1750 straps and basic settings it run for about 8 hours and crashed then. So for me its hard to believe
that people run theste rigs with 1750 straps on the same cards like i have AND also undervolt the hole thing... it would be nice though if somebody could tell me what i am doing wrong.
i ordered 12 more rx 480 and also some Pro btc 2.0 motherboards , so i can have 6 cards on 1 mobo instead off 4. and hopefulle the mobo makes my rig a bit more stable but i dont think it has someting to do with
stability.

So to make things short
- running base bios and base settings ==> rock stable
- running 1750 timings in new bios and basic settings ==> 8 hours stable max !

- now i am running base bios and changed on 1 card the memory from 2000 to 2100 , running stable for 4 hours now and when its stable for 12 hours , i will apply same setting to seconds card , and so on , so on ...

i will keep u guys posted about my progress.

in the mean time , it would be nice to get some ideas of what i am doing wrong or why is it unstable with 1750 timings and base settings? should i make a script that restarts the miner every 3 hours? like this it can maybe mine stable with high hashrate and low power consumption and not crash the whole rig ...