MOBO bandwidth sharing: PCI-e and PCI-X

[aewhistory]

Okay, I'm not sure I have the proper nomenclature to express myself here, but I'm going to give it a try. The way I understand it, no matter how many PCI-e slots and lanes a MOBO has there is a total upper limit to the number of lanes (and hence data) that can be moved along the PCI-e data pathway. However, for MOBOs that have both PCI-e and PCI-X, can this be worked around by offloading much of the workload from the PCI-e lanes--thus freeing most of them up solely for graphics--and moving things like SSDs to a PCI-X controller? Or do they both bottleneck somewhere in the MOBO?

Here is why I ask: I currently used (still) an Asus P5WDG2 WS Pro MOBO. It has 2 each of PCI-e 16x and PCI-X. I'm looking to maximize the efficiency of both pathways.

My follow up is what pathway is the onboard SATA on? This must all bottleneck at the processor, but I'm afraid I don't know enough to really understand and I'm hoping someone can help me out here.

One last thing: is there anything like the P5WDG2 WS Pro for newer hardware? Something that allows the home user to use PCI-X while also getting most of the best of consumer CPUs and GPUs?

 

[aewhistory]

since I haven't gotten any answers I figured I would follow up. I've done some searching on the site here, but nothing quite answers my question that I've found (unless I'm using the wrong search term or overlooked it). As far as I can tell, this is an obscure question.... Do PCIX and PCIe either share bandwidth or bottleneck at any point? I am almost sure that they are completely separate bandwidth-wise, but I suspect that they might bottleneck at the CPU if you're running, say, a whole bunch of SSDs and a couple GPUs, and moving a lot of data down that pipeline.

Does that sound right? I'd trying to understand this and plan this upgrade to Maximize the benefit of this old board.

Many thanks ahead of time!