5870 only shows up as x8 PCIe. MOBO?

I have a MSI 890fxa-g70 with a phenom [email protected] and a radeon 5870 2gb. For some reason it only has a x8 bus connection not x16. Not sure why. the only other thing i have in a pcie slot is a NIC and its in one of the designated 4x slots. This mobo can support 2 cards in xfire both at x16. So I am not sure why My single 5870 comes up as a x8. Even when i stress test the gpu it still stays at x8 so its not some power saver feature or anything. Was wondering if this has to do this the motherboard or not. Thanks. 

Did you try a different slot?

You have it in the top slot? that one is always 16X. Also try moving the PCI-E NIC to a different PCI-E slot as some boards share the bandwidth between slots. And yes you can plug a 4x card in to a 16x slot if you did no know.

I have it in the top slot. It is a 16x slot according to my manual. I will try moving the card to the other designated x16 slot. and see if that makes a difference.  


moved it to the second x16 pcie slot and now it shows x16. Weird. Both the first PCIe slot and the fifth PCIe slot are rated for x16. However the NIC is now in the PCIe x1 slot where it should be. When the videocard is in the first PCIe x16 slot it blocks the x1 port. Maybe it doenst like haveing something in the x4 slot. 


Well, you aren't exactly going to be botlenecked at x8 wit a 5870, but the top slot may be electrically x8.

on second evaluation the 5870 is running at x2 -_-. Not sure why I cant run this at x16 in the top slot. I hate to buy a new video card just to find out it's gonna run at x8...

I have 3 HDD's. 2 128gb ssd's in raid 0 and a sata2 1tb drive. Could the raid be eating up my lanes? also 16gb 4gbx4.

It is my understanding I have 42 lanes...

Just picked up and installed my new MSI R9 280x and it too states that it is running at x8 2.0.....wtf

loaded default bios settings and then re applied my pervious settings. Now my video card shows up as having x16 PCIe 2.0 bus interface. From what I gather There is something with voltage levels on the north bridge or pcie lane that can make the MOBO down grade the bandwidth. Not exactly sure if there was just a stuck setting in the bios or what but all is well now. But I believe it has something do to with something being under or over volted.