I need to understand PCIe bandwidth negotiation, please help

[b82]

My problem is as follows. I want to buy a socket 1156 processor. I also would like to have a USB 3.0 capability in the near future.

I am just beginning to understand the PCIe lane limitations which P55/H57/H55 have. Only 16 lanes of PCIe 2.0. Meanwhile, X58 for socket 1366 gets 36 lanes which I find VERY annoying. Sure, Intel had to differentiate, but why pare P55 down to such an extent that if you ran a graphics card at x16 you could run NO other PCIe 2.0 peripherals? Enfuriating. 18 lanes would have done me fine, but no, it had to be restricted to 16.

There is currently no native chipset USB 3.0 support, so it has to be done with a seperate chip and the data channelled through the PCIe lanes.

Toms Hardware did a review of some of the USB 3.0 P55 motherboard implementations here: http://www.tomshardware.com/reviews/usb-3.0-performance,2490-2.html

I do broadly understand them, and think I like Asus' solution a lot.

Gigabyte take lanes away from the PCIe x16 graphics card, to leave it at x8. But I need to understand WHEN? Whenever the system is booted and the USB 3.0 controller is enabled? Or only when a USB 3.0 device is actually plugged in and running?

For me the difference is crucial, and not explained by Toms Hardware's article as far as I could see. So basically, I need to understand whether PCIe 2.0 lanes are negotiated at start-up, OR whether they're negotiated on the fly according to demand from devices?

What makes me wonder is that Gigabyte's manuals available online, make absolutely no mention of any x16 lanes being given up for USB 3.0.

 

[JackNaylorPE]

Here's the thing .... when I compared comparably equipped Asus MoBos, there wasn't really much of a price difference

http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2010200280%2050001315&CompareItemList=N82E16813131614%2CN82E16813131606&bop=And&ActiveSearchResult=True

 

[b82]

I certainly preferred the Asus solution as described in the article with the PLX bridge. I could clearly see that PLX bridge chip in the pictures of the Asus P7P55D-E Premium in the article.

I want a micro ATX build. I have been looking with interest at pictures of the new Asus P7H55D-M Evo which is advertised as having 'True USB 3.0' as well, BUT I cannot see anywhere in any of the pictures that same PLX bridge.

How can I find out more details of the USB 3.0 solution? No details in Asus' manual or on their website. Reviews that are already out skate over this point. I do not want my USB 3.0 cutting my graphics card down to PCIe x8. Before you reply consider that flight simulators are very PCIe bandwidth intensive. I want that PLX bridge on my micro ATX board, if possible.