I won't give such a high hope. Later, end up with disappointment.
Also, if this new CCC is great, I would install it 1st and then wait for the TwL from Guru3D to make it even more powerful(Modded)! Then, I'll change to the Modded Driver again.   

Flip to the 1st Page and the 1st Post of this AMD Radeon Discussion V3 Thread.
There's a link for Modded Driver(TwL from Guru3D) which I told AMDAthlon to add on this Thread.
You'll get to know about the Modded Driver with that link.   

By the way, I got major performance boost with the Modded Driver from TwL. 

What thermal paste you use? I wanna service mine too.

You got extra FPS in the games(more than that of the WHQL's) and you also got higher scores in benchmarks.   
In addition, sometime, it can be even stabler than the WHQL version. 
Temperature vise, no problem also. 

yes u can bro...

same version 57xx can crossfire . better get same brand , other brand also ok . rent ? no need rent la, get urself 1! 

Let me say this, right now you still have the opportunity to sell your 5770 and topup few hundred ringgits for a better card, because once you CF you have to commit to use those 5770's for a long while...so you gotta choose between sticking to the 5770, CF it or trade/topup for a better card...

Why am I mentioning this? because two 5770 is slightly better than 5850 but cost around RM600+RM600 = RM1200... 5850 is only around  (even below) RM1000 and needs a moderate OC'ing to match those CF'ed 5770s...
Keep in mind CF can sometimes micro-stutters in certain games...

And it's easier to sell one great card then two good cards...

Remember, you're 5770 is still worth it's price right now, as in today...price will depreciate very soon, so decision is crucial... 

CCC 10.7 not out?

Bro, try to play on some heavy game. if you see blackscreen or pc restart, then it means the card need more juice 

No.
When you do underclocked the card, do pay attention to such encounter with  anomalies such as: black-screen (sound still available, but most of the time just black screen only), flickering, vertical lines, pc freezes, etc.
If not, then its' still stable.  I yes, just restart the PC and bump up an increment of voltage and see if stable.
But of course this would usually happen when the card in on full 3D mode when playing games... 

Bro, I used to like to underclock gc and proc bcoz it tests the hardware of how low of the voltage needed to operate stably, plus can be environmentally friendly in the rig 

Definitely Radeon HD6870!
Radeon HD5770 2x CFX is worthless as it consumes a lot of power and produced more heat. Moreover, not all games are CFX/SLI supported. Also, you might encounter some games have weird behavior with CFX/SLI as well.