I've already updated the firmware just after I bought my card.
Almost all issues are gone... my card recovers normally and changes colors during gaming. Performance returned to as it was before my issues.
The only issue that remained is that when my pc goes into sleep then card goes into safe mode. Resetting and shutting down the computer works OK, only sleep mode causes problems - Windows8 ? EPU Engine is uninstalled and switched off in BIOS. Should I uninstall AI Suite II ?
EDIT: Uninstalling AI Suite II (from windows control panel + with tool from this forum) did not solve the issue.
Maybe the only right choice is to reinstall win8 .. is GPU Tweak working better with win7?
M7H / Matrix 7970 P (flashed to R9 280x Matrix P) + 2 x DELL U2713HM / i7 4790k + h100i push&pull / 3 x Kingston 3k SSD 120GB / 1 x Corsair ForceGT 120GB / TridentX 2400 2x8gb / Corsair Graphite 600t case + AX1200i + NZXT IU01 + Bitfenix USB3.0 internal adapter