4th 280x causes crashes after mining starts on GA-990FXA

[koreanjesus]

i have a rig with 4 cards but the 4th card causes crashes after mining for a short time, the card goes to 0/0 kh/s and the temp goes to 511c but the thing is ive swapped the cards around and they all work if there are just 3 and its not a power issue as i have tested by using 3 750w psus daisy chained.  i've also tried different risers and no change im really stuck for what wrong

windows 7
cgminer 3.3.1
cgwatcher 1.3.4
CCC version 13.11

[kikeda]

try cgminer 3.7.2
windows 8

i have the same board and using 5 gpus(280x)

[koreanjesus]

i have the same board and using 5 gpus(280x)

Are you using powered riser or can the board handle the cards on there own.

[kikeda]

2 16x16 powered riser, 2 16x16 unpowered riser, 1 1x16 powered riser.