All 5 series cards can have this problem as unlike the 4 series ( which could could burn out under furmark ) they have a mechanism in place to protect the gpu / vregs from being overstrained.

However as mentioned, quite simply the load furmark can apply is beyond that of any game and AMD simply didn't design these boards/cooling solutions to handle these types of sustained loads. I personally wish they could, but as far as the reference design goes, our hands are tied. Higher performance cooling solutions will certainly help but ideally we will need to see a 5970 with a custom PCB and waterblock to really see them shine ( and not burst into flames and sound like a 737 taxiing in process ) Myself, I won't consider a 5970 running on air.