ATI 5850 Maximum Bus Setting only x2, not x16

Hello

I hope someone can help me with this issue. I purchased a Sapphire Radeon 5850 and have installed it into the x16 PCIE slot in my motherboard. The card does work, however it only gets a Maximum Bus Setting of x2. If I put the same card in the x8 PCIE slot, it runs at x8. I've tried using a different Sapphire Radeon 5850 and get the same result. I've also reset the CMOS on the motherboard and this has not solved the problem. From what I can see, there are no BIOS settings that directly affect the Maximum Bus Setting for that PCIE slot.

My PC specs are:

Motherboard: Gigabyte Technology Co., Ltd. P55-UD6
BIOS Version/Date: Award Software International, Inc. F5d, 18/09/2009
Processor: Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz
Power Supply: Corsair HX 850W
RAM: 8.00 GB (OCZ DDR3 1600MHz/PC3-12800 Platinum)
OS: Microsoft Windows 7 Home Premium

The GPU Summary from CCC is:

Primary Adapter
Graphics Card Manufacturer Built by ATI
Graphics Chipset ATI Radeon HD 5800 Series
Device ID 6899
Vendor 1002

Subsystem ID 0B00
Subsystem Vendor ID 1002

Graphics Bus Capability PCI Express 2.0
Maximum Bus Setting PCI Express 2.0 x2

BIOS Version 012.011.000.006
BIOS Part Number 113-C00201-100
BIOS Date 2009/09/16

Memory Size 1024 MB
Memory Type GDDR5

Core Clock in MHz 725 MHz
Memory Clock in MHz 1000 MHz
Total Memory Bandwidth in GByte/s 128.0 GByte/s

Hi Shadow187

Thanks for the reply. Yes, I've made sure I've got it in the x16 slot (the one closest to the CPU). Is there any way to determine if this is related to the motherboard or the GPU?

Regards