Hi currently in the midst of upgrading eveything in my computer but hit a few problems and am wondering if anyone else has expierenced something similar.

I recently bought a new gpu: XFX R9 380 4gb but when I plug it in and attempt to boot up my computer screen stays blank. but the fans on the card turn on and this is a replacement card so I'm sure there's no fault with it.
When I try to boot up with the same cables only with my older gpu a Radeon HD 6800 series the computer boots up and everything works fine.

I have tried the other video ports
updating Bios
resetting Bios by removing the motherboard battery for 2 min
removing all the old drivers
updating all the drivers
making sure the bios settings are all appropiate e.g. secure boot disabled etc etc...
made sure my PSU is working (just upgraded, it can handle 1300W) so no power issues

The only thing I can think of is that it might be that my motherboard just can't recognise it for some reason? I plan to upgrade my mobo to this soon: Asus Z97 Pro Wifi-AC Motherboard (Intel Z97, USB 3.0, Socket 1150) but atm my mother board is the old : xps 8300 dh67m01 tb0420

my system information is
OS Name Microsoft Windows 7 Home Premium
Version 6.1.7601 Service Pack 1 Build 7601
Other OS Description Not Available
OS Manufacturer Microsoft Corporation

System Manufacturer Dell Inc.
System Model XPS 8300
System Type x64-based PC
Processor Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz, 3401 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS Version/Date Dell Inc. A06, 17/10/2011
SMBIOS Version 2.6
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume2

Hardware Abstraction Layer Version = "6.1.7601.17514"

Time Zone GMT Daylight Time
Installed Physical Memory (RAM) 8.00 GB
Total Physical Memory 7.98 GB
Available Physical Memory 5.21 GB
Total Virtual Memory 16.0 GB
Available Virtual Memory 11.3 GB
Page File Space 7.98 GB
Page File C:\pagefile.sys

Any advice would be appreciated:)