High cpu and crash if using 4th GPU

[rjSampaio]

hi all
got a litle big problem here

if i try to run my 4 gpu on -I 13 the cpu usage goes 50% (not the miner, but "System NT Kernel") and crash in no time

this only happen on the 4th card, if i use -I 13,13,13,12 it dosent crash, and cpu is around 2%

hardware/software

H81 Pro BTC
4x Asus 280x DC2T
Windows 7
AMD driver 13.12
Sgminer

already test changing the order of the cards and slots, it dosent mather, the 4th is the black sheep