Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
I'm with Sonda, got the cheapest powercolor 7950 and have gotten it up to 1320/1800 with an EK waterblock. Sounds like the issues with the twin frozr are only cooling related if you're only seeing issues at the 75C mark.
I'm having issues with multiple runs of Heaven actually getting lower...