Crossfire compatibility with mobo/case

[neit]

I have a fractal core 1000 case and ASRock z77 pro4-M that's running well with a HD 7850 2gb gpu.

I am eyeballing a possible gpu upgrade (for higher resolution moderate gaming), more specifically wondering with new 7850 prices hitting ~$100 sales if crossfiring is a good idea. My concerns are that my mobo requires me to put the second gpu in pcie slot 4, but my understanding of the case is that it would put it below the 4th expansion slot. Can I do crossfire with my current case and mobo?

Would getting a single slot 7850 work fine in this situation? I'm not uptodate on dual gpus, but last I recalled the memory of the main gpu was used, does it matter if the second one is 1gb or 2gb?

 

[Charlie98]

Depending on the size of the GPU card, you may have to pull the HDD 'cage,' or move the HDD up to the top position.

I think you have to have GPU memory of the same size... memory use is duplicated across both cards.

 

[mfenn]

I would worry about the x16/x4 split before I even started thinking about whether or not it would physically split. Crossfire/SLI on lower midrange cards is inherently more prone to microstutter because each card will be more likely to run at absolute max with no buffer for more intensive frames. Add to that the fact that one card will won't be able to receive data as fast as the other. Add to that the fact that 7850's don't have AMD's new XDMA engine, and you have a recipe for horrible microstutter.

I'd wait until I had enough cash to get a good single-GPU upgrade. Even an R9 270X or GTX 760 would be a nice upgrade.

 

[neit]

Having cash isn't the problem so much as I can easily justify an additional $100 vs 200-250... I haven't hit any major problems yet, I can readdress this once I get a 1440p or 4k display and start having real issues.

Do games that support mantle have reduced microstutter problems? I thought I read about that but haven't dug in too deeply.

 

[mfenn]

Mantle is designed to reduce CPU load when playing games, it won't help in the GPU-bound scenarios where microstutter crops up. Also, Mantle is supported by a tiny fraction of games out there, so I personally wouldn't make any purchasing decisions on the hope that it catches on.