Originally Posted by simonizor
What does the PCI card do? Odds are that there's already a USB version of whatever the PCI card does.
PCI stands for peripheral communications interface. Its a type of slot found on your motherboard. Back in the good old days PCI was considered fast when compared to ISA (integrated slot architecture, which was very user friendly compared to what we had before). It was used for many things including sound cards like Sound Blaster, and video cards like Trident. Eventually when 3D accelerators came around it was used for those as well, but as they got faster people found the bandwidth of PCI was too small.
So the AGP (accelerated graphics port) standard was formed and it had considerably more bandwidth, in fact so much bandwidth it was reserved exclusively for high end graphics cars and I dont believe any other devices were ever used in it. AGP was increased in speed 8 times over and served the industry well for a long time. However it was deemed that too much large crap was still on motherboards and another standard was needed to both increase bandwidth and save space. For a while the two main contenders (PCI-X and PCI-e) competed with each other but eventually PCI-e won the day. PCI-e X 16 is now the standard for video cards because of the insane bandwidth needed. And if I'm not mistaken its a little longer than the AGP slot.
PCI-e X 1 is the standard for small devices like modern audio cards, SATA controller cards, and USB expansion cards. Now while all 3 of those devices are commonly found on all modern mainboards, people still like the option to add more or better devices. If you arent happy with the 4 USB headers found on the mainboard (or dont have enough USB ports on your case, if any) you can slap in a USB expansion card with your PCI slot and have 4 or 5 more ports. However, USB 2.0 requires a fair amount of bandwidth and USB 3 requires even more. The old PCI bus doesnt have that kind of bandwidth, so its pretty much a guarantee you need to use your PCI-e slot, if you have one available.
The OP is asking for a product that probably doesnt exist because theres no way in hell you could have all 4 USB ports running full speed on a PCI bus. But of course we all know damn well its tough to get 4 devices running at full speed at the exact same time anyway. The only thing I could think of is 4 external hard drives, two pair running in RAID 1, and you copy massive files from one logical drive to the other.
Why you'd do that is beyond me. I guess backup of a backup.
Truth be told I dont think the PCI-e X 1 bus has that much more bandwidth than the old PCI bus. I think the idea is to just make the slots shorter because you can and because motherboards are starting to run out of room. Every time we move to a smaller standard for things, they shove more shit on there. SATA replaced PATA but now they have 3 times as many connectors on the board. We also seem to be putting more USB headers on the boards as well, which makes sense cuz I've seen cases with 6 USB ports on them.