Sapphire r9 270 can't go over intensity = 13

[Forexperiments]

Hi, I had a system with a Radeon 5970. It worked fine at i=18, no hw errors.
Now, I changed the 5970 with two brand new sapphire r9 270, i get lots of hw errors if i>13.
Why is this? The PSU is not powerful enough?

[satsumi]

-g 1 -w 256

Higher -g will cause hardware errors at any intensity above 13.

[CMD7790]

you could try either -I 17 -g 1 --thread-concurrency 12000 or -I 19 -g 1 -w 256 --thread-concurrency 16384.

that should give you a good base line. you probably need to tweak the settings a bit though.