Graphics running too slowly

I have suspected some kind of problem with my desktop computer for quite some time now. Whenever I play games(anything requiring a bit of graphics power: Left 4 Dead, WoW, Guild Wars, etc.), the game runs very slowly.

At first, I simply thought my graphics card was not powerful enough to run these games at their maximum settings. In fact, I have had to run most of them at fairly low settings. At the time, I didn't really have the best video card.

Then, I got a GeForce 8800 GTS 512. The problems still persisted, although of course my graphics capabilities did jump a bit. I still thought that perhaps my expectations were simply set too high. At one point, my power supply died, and I hooked my laptop up to my monitor, keyboard, etc. This laptop's graphics card was not even as powerful as my previous desktop video card, let alone this newer one. However, I could max out the settings in Guild Wars and the game would still run smoothly in most areas. This was not the case on my desktop, even with the settings set to their minimums.

Anyway, we recently put a GeForce GTS 250 in my fiancee's computer, and as expected it runs beautifully. However, yesterday I put the exact same card in my desktop, and I STILL cannot run games without setting most things to their minimums.

Obviously, something is definitely wrong with my computer. Even though it shows up as a graphics issue, I am certain that it is not a problem with the graphics card now. What else could cause this problem? Could it be a bottleneck somewhere else?

My other specs are:

Mobo: Asus A8N-SLI 939
CPU: AMD Athlon 64 X2 4400+
RAM: 2 gigs

I have all the latest drivers, DirectX, etc.

 

Oh, I should add that I just opened up the Nvidia driver settings on both desktops (the computers with identical video cards). All settings are identical. Also, I checked the System Information thing, and all numbers are identical, save one.

The Bus value is different on the two machines. I don't know for sure what this is, but I believe it might well be important. On my computer, the Bus value is PCI Express x1. On hers, it is PCI Express x4.

Now, I am not positive, but I thought that these should both be PCI Express x16. I am pretty sure that both motherboards have these slots. Since I bought both motherboards from Newegg (years apart, obviously), I will link to those pages, and maybe someone can explain the different PCI Express slots to me.

Here is the Newegg page for the motherboard on my computer: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131524.

And here is the Newegg page for the motherboard in my fiancee's computer: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131331

My motherboard seems pretty straightforward, there are two PCI Express x16 slots and two PCI Express x1 slots. When I put the card in, I put it in one of the graphics card slots. It seemed quite obvious which slots were for the graphics cards, as the board has two slots with a little slot in between in case you want two cards at once.

Her motherboard is even more confusing to me, as it has three PCI Express 2.0 x16 slots. Is there a difference between PCI Express 2.0 x16 and PCI Express x16?

 

It's a possibility the programs running in the background while are slowing the games down.

Download Gamebooster.

Once you have it downloaded and installed it. Open Gamebooster, You should be presented with a simple interface like the one below: http://i732.photobucket.com/albums/ww328/lifetweaker/random%20junk/Untitled.jpg

Whenever you decide to play a game just click "Switch to gaming mode!"

Once you're finished playing a game Open Gamebooster, you will be presented with the same interface. This time select "Back to normal mode"

 

Your CPU is bottlenecking the graphics card. You could also use more RAM (but that's not the main issue here).

As for the difference between PCI-E x16 and PCI-E x16 2.0, it has to deal with bandwidth. Read up on wikipedia if you like:
http://en.wikipedia.org/wiki/PCI_Express

 

Oh ya, changing the slot did it. WOW! I have had three different video cards on this thing over about three years, and I never noticed this until now. I feel incredibly stupid. When you only have one video card on this mobo, one slot is x1 and one is x16. I managed to find that online once I knew to look for stuff about the bus value. So thanks everyone, my games are running WAY faster now (40 fps gain in WoW, for instance).