How do I update my PCI Express?

Its just a revision. Last I checked, The PCI-E bus supported is dependent on you CPU, MB and Add in card. 2nd Gen Intel supports 2.0

Take this from wikipedia -

"PCI Express 2.1 supports a large proportion of the management, support, and troubleshooting systems planned for full implementation in PCI Express 3.0. However, the speed is the same as PCI Express 2.0"

Your 6670 wil be just fine

you don't need to update anything. PCIe 2.0 and 2.1 are backwards compatible, and you're not losing anything if the performance difference between 2.0 and 3.0 is anything to go by. unless you plan to put that GPU in a PCIe 1.1/1.0 slot (i doubt there's any in your motherboard), you don't need to update anything.

http://en.wikipedia.org/wiki/Pci_express#PCI_Express_2....

My graphics card wasn't working though... that's the reason I assumed I needed to update it... Can I know anyway?

Yeah but my card still doesn't work... Can you tell me how to update it anyway?

Have you check to see if a BIOS update adds this functionality? To allow 2.1 Cards into 2.0 Slots? The BIOS readme should say. If it doesnt say anything about that then dont worry about the BIOS update.

What exactly happens when you try to use the 6670?

You don't need to update anything. PCIe 2.1 is compatible with PCIe 2.0 out of the box.

@OP: What are your full specs?

It just flat out doesn't work. I plug it into my PCI-E slot, connect it to the DL DVI adapter with my VGA, turn the computer on, and I get a black screen. The monitor turns on and my computer turns on, but I get nothing showing up on my screen.

Could you list your full specs including monitor model?

This is pretty much what was in the full description, so I can be as specific as possible.

2nd Gen Intel Core i7-2600 Processor with 8MB L3 cache and 3.4GHz processor speed with Turbo Boost up to 3.8GHz.

8GB DDR3 Memory upgradable to 16GB

Nvidia GT 520 Graphics

I don't think the monitor was the problem, since I tried this with 2 different monitors.
I don't know the exact model's, but one of them is a dell, and the other was a hanns g.

Motherboard?

I only know it's an ASUS.... Sorry. I think it's a ASUS desktop PC CM6850 Series??? That's what it says on the computer properties but I'm not sure if that's it.

We need info about power supply unit as well. And hard drive configuration would be nice as well.

How do I find that? Sorry for asking a stupid question but I really have no clue...

Start
All Programs
Accessories
System Tools
System Information

I use this program. It's completely free and gives detailed readouts of your system specs.

http://www.cpuid.com/

Download the CPU-Z program.

None of that will show the power supply unit.

@OP: you have to open the side of your PC and read the label.