SSD running at half speed. Please take a look

Hello Everyone! So after reading dozens of threads about the problem im having.. i have to call uncle and ask for help. I installed a new ssd into my pci-e slot of my Dell precision t7400. I found it to be the cheapest way to get the fast speeds i was hoping for. I have a SanDisk SDSSDA240G installed into a PCI-E SATA 3 adapter(Images: pci-express_01 / ssd)info). Im running windows 7. I have made sure i am in AHCI and that i am running the correct Bios. The Card is in the First PCIE (Slot1) and my graphics card is in the other PCIE (Slot4). It is plugged into the only SATA port that was available (Image: MotherBoardSetup). Ive run the benchmark app and it seems like its only running 3G instead of the 6 that i was hoping for.
I have Dual quad cores Intel Xeon e5450. EVGA GeForce GTX 560 2GB Graphics Card. 32G of DDR2.
Windows 7.
Im a 3D artist and use multiple 3d programs. I know its running fast now, but any extra would be helpful. Can anyone please take a look at these pics and help me out?
Thanks -DT

I also have this pic from when i startup...and one of the PCIe card i bought...if that helps.

Thank you. Yeah i was trying to get best bang for my buck. I Have 4 storage bays which are already full with storage drives. So i thought this would be the best bet. Is running a drive through a PCIe slower than if i had a drive in one of the bays? Or is it because i bought cheaper hardware? And you said you were surprised it worked at all. Is it because things are mis matched?
How am i gonna take out my GPU when my monitors are plugged into it? Please forgive me if that is a uniformed question.
-DT

Yeah i would have paid that for a stand alone drive, but my other drives have much more storage on them. I do a lot of cg work so i need those drives. So i opted for the pci-e. Which does have its own power source. You said it had 2tb..were you referring to ssd?
-dt

Plus i read that PCI-e would be faster than a stand alone drive because "it can handle greater data traffic throughput and I/Os as they use the much faster PCIe bus to connect directly to multiple channels of flash memory". I dont know if thats true but it did help sway me to get the PCI-e.. maybe i just got the wrong drive to plug into it.

So i think i answered my question with a little more researching. It turns out the pcie adapter i bought is x1. so it will only allow 250mb per lane. I hope that sounds right.