Sapphire 4850 512MB stuck at PCI-e 1x

[imported_dorian]

Ok, I've been having some performance issues at games, and now I noticed that my video card is stuck at PCI-e 1x, when it is supposed to be 16x. I checked both in GPU-Z and ATI Catalyst, and they both show it as 1x. I never checked this before, so I don't know if it was already like this when I bought it or not. But recently there was a drop in game performance that I couldn't explain otherwise.
I have the latest driver installed (9.7) and the latest BIOS for my motherboard (Gigabyte P35-DS3L). I didn't find any settings in the driver or in the bios that could change the Pci-e bus speed.
Anyone has any ideas how/if I can fix this? I'm afraid that if the card is defective, they won't replace it because it wasn't like that when I bought it, even though it's still within warranty. Temperature has always been fine, and my PSU should be enough for it (Corsair 550W).

Rest of my specs are:
C2D E8400 3.0GHz, never overclocked
2x2GB G.Skill DDR2-1000
Windows Vista Ultimate 64

 

[Fox5]

Reseat the card, it may not be making proper contact in the pcie slot. Perhaps the screw holding it in is overtightened, try placing it in without tightening the screw first and see what it reports.

 

[imported_dorian]

Reseating the card put it back at 16x and game performance seems normal again, thanks!
I'll probably get a new case though.. the place where you put the screw to hold the card is too wide, and doesn't hold it properly.

Also, I may have done something stupid while reseating, and my PC wouldn't boot. After switching memory modules around, I found that I could only get it to boot by putting the modules in different channel. Will I lose a lot of performance by not having Dual Channel?