Wanting to upgrade my XPS 8300

[Do_The_Panic]

I am currently looking to expand on my xps 8300. I am looking to replace the case and PSU unit currently and have a budget of $200. I have heard rumours of dell motherboards using a different set as far as screws than other companies and wondered if that might present a problem in choosing a case. My idea for a case is something with good ventilation and ready for water cooling when i get there. Not super worried about looks to be honest and my power supply maybe a 600-650W. I'm looking to throw a ASUS gefore GTX 560 Ti in it when I get the money for it. I am looking for help in choosing the right components and hope that you guys can help. just so you know my rig is a i7 2600 w/ 8Gb RAM GDDR3 a Radeon 6450 HD 1Gb GDDR3 a 500 Gb HDD and a 460 PSU if you need any more specific specs just ask I'm willing to give them thanks for the help guys!

 

[Smeg45]

What is the 12V info on the PSU? I'd look into replacing the PSU and than putting in a 7870 assuming everything will fit. You should have built your own PC from the get go . . .