The common suggestion would be either the phenom II x4 965 or 955. the difference being the 955 is 0.2GHz slower.
I recommend the x4 945 though. At 3.0GHz, it is 0.2GHz slower than the 955 and has a locked multiplier. Normally about $20 less than the 955, it is well worth it and still won't hold back your radeon 5850 unless you play a CPU bound game like FSX.
which doesn't perform well with the x6 1055t.
Could you expand on that? Because this affects and is related to my recommendations. The 1055t should perform very well and not hold back your graphics card on any modern game.
Maxing out settings depends on your resolution too, a 5850 coupled with either Phenom II X4 955/965 or X6 1055t can handle games fine on resolutions like 1080p.
Like Enzo Matrix said,please clarify your statement,why a 1055t won't perform good on that motherboard ?
Well on the mobo the x6 1055t is not really compatible with the motherboard in which you have to update the bios. I gaming experience seems really limited. On GTA 4 for example at medium settings, 52 frames, 1600x900 res it still seems to be choppy. I posted a forum earlier in the year about this problem. They said that the mobo I have isnt barely compatible with the new processor.
Lol sorry about the barely compatible =P But they said that the 790 series of the asus mobo arent made for the new x6 yet. The 780 series is what was made for the new x6. So therefore from what i see about this is that the x6 doesnt perform right like it should. Btw, also i play other games like WoW, BFBC2, and other fps shooters. I now realize that GTA is a buggy game, best the thing is i dont understand how people have basically the same setup as me, but usually have a x4 with the mobo not the x6. It seems there able to max out any game. Im still confused on what to do.
Lol sorry about the barely compatible =P But they said that the 790 series of the asus mobo arent made for the new x6 yet. The 780 series is what was made for the new x6. So therefore from what i see about this is that the x6 doesnt perform right like it should. .
wrong. If it works and is running at the correct frequency and turbo works, then there is no performance issues. it will work 100% as it should.