TP-Link PCIe slow connection speeds

I have bought a cheap Wireless-N TP Link WN871ND PCIe card for my PC after an upgrade, but now its in my DL speed has dropped from 30Mbs to 1-2Mbs.

I'm using a virgin super hub (not the new one), my PC is no more than 10ft away (reason for wireless is there is a wall in the way), and I had no issues when using a TP-Link TL-WN821N USB dongle. I had the same issue when using a different PCIe wireless card in my last home too, same router but I put that down to bad router position as it was on the other side of the house.

I've checked my other devices and they still get 20-30Mps DL, so it can't be the router. I was wondering if PCIe had any speed restriction options in windows or bios?

PC Spec:

TP-Link WN781ND PCIe Wireless Card(*)
AMD Phenom x4 3.4Ghz
6GB DDR3 RAM
Asus M5A78L-M LX v2 Mobo
2x500GB WD HDD(1x*)
EVGA Geforce GTX650 2GB(*)
AVP Defender 200 K1 Case(*)
Corsaire CX500 500w PSU(*)

(*) = New from upgrade, if that helps in any way

This is really starting to bug me and I'd prefer not to be drilling holes in the walls..

Thank you in advance for any advise! I'm really stumbed on this one =/

 

While a pain, I would temporarily move that computer into the same room and see what happens. There may be metal pipes or wires inside that wall causing interference. Or other electronics in that room affecting performance.

If the card's antenna is in a vertical position, try moving to a horizontal orientation or vice versa.

Also - you need to verify models numbers. When I search on Wireless-N TP Link WN871ND, I get this "PCI" card. Note, that is PCI, not PCI express.

@David - that link goes to a WN781ND - not a WN851N.