Crossfire query?

[Welsh]

Now, I have an Ati 5970HD.....

Before the 6000 series came out, I saw something which said the 5970 could be crossfired with a 5870 (but not the other 5 series models.) Now, this being true..... I'm wondering, can the 5970 be xrossfired with a 6000 series? I've googled and it keeps showing me [f*cking] performance graphs for 6000 series cards :|

Second question is this:

They don't sell the 5970 anymore (unless on ebay where it's like 450 used....what i bought it for new.) Would it be worth me bothering to crossfire with a 5870 (performance gains be much?) or should i just put my money away and wait for the next ATI cards/save for one of the new Nvidias? My cards still running everything perfectly and have had no performance complaints with it, except it sounds like a [f*cking] jet engine about to take off when the fans are above 60%!!

[LuMbErJaCk]

Don't fix it if it ain't broke
You can make profiles in the Catalyst Control Center, I had 3: default, game and idle.
On idle i turned down the cpu and mem sliders as far to the left as possible and the fanspeed at 33.
In default and game all sliders to the far right and the fanspeed respectively at 50 and 45%.
Keep an eye on the temperatures with Hardware Monitor and u can reduse the noice a lot.