HP z820 ??? DMI MAX Bandwidth + USB PCIe 3.0 Card vs USB 3.0 Motherboard

[taccess]

z820 block diagram :

http://manualmachine.com/hp/c1d80ut-small-form-factor/905921-user-manual/page:10/

Hi

Regarding the usb 3.0 on the z820 motherboard, i cant find any information on the block diagram

of the front two usb 3.0 ports so i assume they are identical to the rear usb 3.0 ports which have to go to a USB 3.0 controller TI7340 first then to the INTEL C602 controller via x1 connection speed (500MB/s) and finally to the CPU via DMI

( Direct Media Interface ).

1) what is the DMI Bandwith maximum on the z820 from the C602 to CPU 0 ?? 5 GT/s DMI  

I am under the impression that its DMI 2.0 and that equals PCIe 2.0 which equals 500MB/s per lane if so how many lanes are there ? x4 just trying to work out total bandwidth

2) if i decided to use a USB 3.0 PCIe card ( for a direct CPU to USB 3.0 connection). Would i decrease " slightly " the latency because now i am bypassing the TI7340 + C602 controllers ?

[DGroves · Accepted solution]

if usb xfer speeds are critical to you, ignore the onboard usb ports and get a usb 3.0 card that has a "PLX" chip on it

http://www.highpoint-tech.com/USA_new/cs-product_RU.htm

check ebay, sometimes the cards show up for around 40/60 dollars

these cards are able to supply full (5MBps) to all ports at the same time (@2MBps total) they are not cheap, but they do work!

as for the z820, all usb 3.0 ports share bandwidth, as such each device added will slow down the r/w speeds

and the max bandwidth is 5GBps shared across all 4 onboard ports