HD 4850: Running at PCI-E x8/x4 instead of x16, Help wanted!

So I realised that my HD 4850 wasn't performing as well as it should be so I loaded up GPU-Z to find the problem. It turns out that the Bus Interface was PCI-E x16 @ x1. Knowing possible fixes to this problem already, I opened up my case and cleaned out my PCI-E slot. I rebooted and ran GPU-Z again. This time it said PCI-E x16 @ x4. Figuring that it was solely a dust problem I cleaned my slot again, and this time GPU-Z gave me PCI-E x16 @ x8. I've cleaned it 3 times now and it won't give me full x16 performance, and sometimes it's at x4, sometimes x8. Does anyone know how I can get my card to run at x16 like intended?

Here's some information about my setup (Info gathered with Everest Ultimate Addition and HWiNFO):

OS Partition 1: Windows Vista Home Premium 32Bit SP2
OS Partition 2: Windows 7 Ultimate RC(7100) 64Bit
(Problem exists on both OS)
CPU: AMD Athlon 64 5200+ X2 2.6GHz Dual-Core Processor
RAM: 3GB DDR2 333.3MHz Nanya Technology SDRAM
Motherboard Model: Acer F690GVM
Motherboard ID: 06/25/2007-RS690-SB600-6A669FK8C-00
Motherboard Chipset: ATI RS690(M) + SB600
Motherboard Slots: 1 PCI, 1 AGP, 3 PCI-X, 1 PCI-E x1
(PCI-E x1? I have my PCI-E 2.0 x16 video card in this slot. Mustn't this slot be x16 to even fit the HD4850?)
BIOS Name: Acer, Phoenix - AwardBIOS v6.00PG
BIOS Date: 06/25/07
PSU: Corsair HX620 620W Modular Power Supply
Video Card: Sapphire ATI Radeon HD 4850 512MB GDDR3 PCI-E 2.0 x16
Monitor: Acer X203W

Let me know if you need anymore information.

Solutions I have tried:
Disabling "PEG Force x1" - There is no "PEG Force x1" option in my BIOS to disable.
Set the NB Vcore to 1.45V or less - There is no option to edit the NB Vcore in my BIOS, NB Vcore isn't even mentioned anywhere in my BIOS.
Tweak the PCI-E Reference Clock lower or higher - There is no PCI-E Reference Clock option in my BIOS to edit.
Clean the PCI-E Slot - I have done this 3 times now. I've blown into and onto the slot and card, wiped with non-lint cloth, and even used a fan close up on the slot, card, and surrounding areas.
Revert to Default Settings in BIOS - Didn't fix the problem.

I would greatly appreciate any help with this problem as it is frustrating me and I can't seem to solve it by myself.

Do I need to clean the PCI-E Slot better? Do I need to change a setting somewhere? Is my slot somehow set to run at maximum x8? Do I need to buy a new video card or motherboard? I'd like to exhaust all other options before buying new hardware, however.

I think the answer is that x8 is the maximum the slot can run at because the motherboard is permanently set to run it at 8x. Can anyone confirm this? I don't want to buy a new motherboard if I don't have to.

Hi, I can't seem to find your board anywhere. But you must have a PCI-Expressx16 slot to get your card to work, but the thing is your slot will be PCI-Express X16 1.0. So in other words it will run at x8 mode (2gb/s) bus speed instead of 2.0 (4gb/s) bus speed. So really your motherboard is limiting your card.

Ok, thankyou for the input. People on other forums seem to think this as well. When I buy a new motherboard I'll be sure it has a PCI-E 2.0 x16 slot.