Reformatted old Dell desktop, can't get dedicated GPU to work.

[Divaya]

I have an old Dell Inspiron 530 that's about ~7 years old that I've reformatted and reinstalled stuff with the original disks.

[U][B]The issue:[/B][/U]
After reformatting the computer seems to [I]only [/I]want to use it's Onboard Intel G33 (Integrated GPU), and refuses to use the dedicated GPU I have installed (nVidia GTX 460)

(also, it "starts" up and then stops starting up, then starts up for real, dunno what that's about).

[U][B]What I've tried:[/B][/U]
- I checked the BIOS and it was set to use whatever was in the PCI slot (only two options: onboard and PCI)
The card I have installed is a nVidia GTX 460, and it's been installed in there since basically forever. I haven't touched anything on the inside since 1~2 years ago.

- I also tried to disable the driver for the onboard graphics, but that didn't work. Nothing thus far has actually worked at all.
I know that it definitely use to work since I use to play Battlefield 3 and stuff on it only a year or two ago.

- Because the onboard graphics is used on boot, I can't install the other GPU's drivers

- I tried Googling, but I can't seem to get the machine to boot up using the nVidia card at all, no matter what I've tried

[U][B]Specs:
[/B][/U]Quad core CPU (2.4GHz per core)
Intel G33 onboard
nVidia GTX 460
730 watt PSU
3GB RAM DDR2
500GB HDD
Windows Vista (too lazy to by a new OS for it) 32bit Home Premium

[Drumdevil]

Check if there is a BIOS update for the Inspiron.
Did you properly connect the power cables to the GFX card?

[Divaya]

I'll check for that update, and yeah, the power cables are fine. The card is on & powered for sure, and the fan is running.

[editline]10th July 2013[/editline]

Alright, I figured out the problem (I think).

Removed the old GPU (GTX 460) and swapped it for a spare GPU I had (GTX 560), I wanted to see if it was a problem with the card. Started the machine and it booted on the first attempt instead of trying to boot several times and failing.
My advice to anyone who's computer is failing to boot a few times: Your hardware is dying :'(

(also I updated the BIOS and it added a sweet new boot menu but that's about it)