I've had two of them in Cross Fire since Oct. of 2008 and never had any trouble I got them in an Alienware ALX R-8, I am able to run any game out in 1920x1080 at High or Max settings. However I just ordered a 7970 and plan on getting a new setup/system next year when Haswell comes out.
The main reason I'm getting a 7970 is that it supports DX-11 and you can't play Crysis 3 unless you have DX-11.
Anyway, the 4870x2 has been a great card for me, especially with 2 of them in x/fire. the only problem is I am not able to use the last processor it always says disabled adapter so I have 3 enabled adapters and one disabled, so it must be a motherboard prioblem.
BTW, they are very quiet at least in my machine, I have a water cooled CPU and a great Alienware case but they certainly don't sound like a jet engine. Actually I love my 2008 system, but I guess the grass is always greener.