Crossfiring 4800's

[J-I-M]

Crossfiring 4800's - But is this set-up worth it?

Evening OC's
I've just been offered a MSI R4850 OC Edition for £40 and i'm tempted to take it as it's not a bad card, though my question is how will it perform against a 4870.

As far as i know all the 4800's can be CF'd but the more powerful card will run alongside the slower card but can the 4850 be overclocked to the 4870's standards? They're both 512 and i game at 1920x1080 P and i do notice the lack of memory my 4870 currently has at given times. Would it cause more complications than a bonus performance?

And finally would an E5400 at 3.8 ghz bottleneck them severely?

Edit: Excuse my ignorance i forgot to add the mobo they'd be both going into, i'm using an Asus P5Q Deluxe and powering them would be an OCZ 750W ATX12V v2.2 and EPS12V.

 

[Si105]

The 4850 uses GDDR3 so no you can't overclock it to match the performance of the 4870. It will perform okay in crossfire but for another 40 quid you can get a 4870 new.

http://www.overclockers.co.uk/showproduct.php?prodid=GX-100-HT

I don't think there would be a CPU bottleneck. Not that many games use quad anyway. Some of the newer ones do of course. I know there are issues with 4850/4870 xfire so you're probably better off getting the 4870 or getting a second hand 4870.

The psu would be fine to power a dual 4870 or 4870/4850 crossfire. Of course the memory is still low for 1920x1080p so if you could you might as well get a new video card with 1GB memory. Maybe a GTX 470/ATi 5870?

 

[J-I-M]

Lovely, That's a shame about the 4850 however great news about the £40 extra for another 4870, i could upgrade to one of the newer cards however i've not majorly found a reason to my 4870 is still performing very well in more or less all of todays games and seems a waste to rule it out untill full support for DX11 is out for most of todays gaming.

I only notice stutters under quite heavy load in APB and Global agenda and so forth where the 512 memory can't handle, however I thought chucking in another 4800 for now would take the load off and for the time being, as i believe there's only 5-6 games out that currently support DX11?.

Would there be a noticable difference in performance as i'm only currently getting 35 odd frames in APB with the 4850XFw4870 with the 70 dropping to DDR3? i can almost certaintly get it for £25 which is a bargain to say the least as the seller has absolutely no use for it, where in the future i can chuck it in another computer when i'm done.