Graphics Card Replacement

Graphics Card Replacement for Studio XPS 435MT

Hello guys,

My system is Studio XPS 435MT brought in mid-2009. I was having some display issues because of which I replaced my old graphics card(ATI RADEON HD 4850) with RADEON HD 7300. My display issues are resolved but the card is weak and a little sluggish on even some old games.

I am also facing starting up issues which I have posted here.

So I was thinking of changing this card with a card which atleast matches the performance of the old card(ATI RADEON HD 4850).

I am based in India and the choice of graphics card is limited. The prices are also a little high nowadays.

My system is Studio XPS 435MT brought in mid-2009 and my specs are:

Model: Dell Studio XPS 435MT

Current Graphics Card: REO RADEON HD 7300
Old Graphics Card: ATI RADEON HD 4850
Processor: i7-920
Ram: 6 GB DDR3(Currently only 4 GB working)
Motherboard:0R849J DX58M01
PSU: 360W MAX
+12VA & +12VB TOTAL 300W MAX
+5v & +3.3V & 12VA & 12VB TOTAL 350W MAX
Bios: Brand: Dell, Version:1.1.1, Date: 05/05/2009

Windows 8.1 Pro

Everything other than the Graphic Card is as it came originally.( I have not replaced any component.)

Choices availaible to me(in my budget) right now are:

1.)Nvidia Geforce GT-710(DDR3 and DDR5 variants available)
2.)Nvidia Geforce GT-730
3.)Nvidia Geforce GT 1030(DDR4 and DDR5 variants available)

I would like to ask if these cards will work on my system without any other hardware change to be needed? I had read in some forum about the cards requiring UEFI. Is that true? As per System Information in Windows, my BIOS mode is Legacy. Would they work on my system? Would it depend on the manufacturer(ASUS, Gigabyte etc)? Would they provide the same or better performance than my ATI RADEON HD 4850? 

Thanking you in advance