PCI EXPRESS SLOTS

[atheodor]

Hello guys, this is my first post but I am hardware geek and Linus fan for a long time now. In my rig I use a Rampage III Extreme motherboard which has 4 PCI Express x16 slots for graphics cards which operate at dual x16 or x16, x8, x8 or quad x8 depending on how many graphics cards you use. In my case I use 3 x PNY GTX 580 1.5GB in slots 1,2,3. Although, I use the 4th PCI E x16 for a USB 3.0 PCI E card in order to connect my case's front usb ports. Does this make my graphics card operate at x8 x8 x8 since all 4 PCI-E x16 are used or does it work at x16 x8 x8 as it supposed to because I have connected another PCI-E device and not a graphics card for SLI? Has any of you tested or done any benchmarks on something similar? Is there any way to test if my GPU's operate at x16 x8 x8 or x8 x8 x8 ? 

 

Thank you in advance,

 

Aris

 

Edit: I will also include my full component list in case something is relevant.

CPU: i7 980x Extreme 6-core 3.3GHZ OC @ 4.0Ghz
Motherboard: Asus Rampage III Extreme
GPU: 3 x PNY GTX 580 1.5GB
RAM: 6 x Corsair XMP DDR3 2GB @ 1600Mhz
CPU Cooler: Corsair H70 with dual SP120 Performance Corsair Fan
SSD: 2 x 120GB OCZ Agility 3 in Raid 0
HDD: Seagate 1TB, WD Black 1TB 
PSU: Corsair AX 1200i 
Case: Corsair Carbide Air 540

[Glenwing]

X58 has 36 lanes, so you should still have enough to run x16/x8/x8 with an x1 card in the last slot.