EDIT: Did a copy and paste of next sentence accidentally
Should have been - " Does my psu supply power to my motherboard? "
Not - "I am able to run just fine on integrated graphics, then wouldn't that rule out the possibility that my psu is the problem?"
Yes it does run the motherboard - No, it does not necessarily rule out the psu, but
does point more toward a faulty gpu or motherboard.
All three psu rails go to the motherboard +2 - +5 & +12V, via the large connector (ATX)
with multiple wires, and another +12V connector for the cpu.
I was only having you check the motherboard voltage as part of the process to verify stable current.
- If the psu is faulting it would not necessarily have a problem when the gpu is not installed , but
that little bit more power that is drawn by the gpu could be more than the psu can handle.
More commonly though psu issues manifest when running a game as the gpu draws significantly more
power under load than at idle.
However, while booting into Windows and loading the drivers I'm not sure if the gpu starts at full clocks and power draw or not. I do know the fans will spin up to max speed for a short time before
the drivers are loaded.
"...GTX 650 because I can't even turn the computer on long enough to log in before crashing."
Ooops - Was overlooking that minor detail when suggesting monitoring the voltage, wasn't I ?
Are there no 'Post' beeps when the drivers are installed and the machine fails to boot into Windows ?
It's sounding pretty grim when you cannot even boot into Windows with the Nvidia drivers installed.
The drivers enable the gpu, and Safe Mode is not an option for troubleshooting because it disables
the drivers..
It's still guesswork without being able to verify the card and motherboards PCI-e controller by
part swapping.
If the motherboard has another PCI-e slot ( X8 is OK for troubleshooting) you could try the card in
that. This still only tests the physical slot though, not the PCI-e controller. I don't know how the
controller is tested.
Even re-seating the card and power connector may help *Cross fingers*
Beyond this, the only way to isolate the issue is take the machine to a technician. Never know, he
may find something simple. It's a lot easier troubleshooting up close and personal.
"I don't think I can make a warranty claim on a warranty claim :/"
EDIT (again ;) : After re-reading I see you had the old card for close to full warranty period so you are not
likely to get an RMA from this one as it would be warranted from the date of the 450.
If it's only been two years eleven months you still have a chance.
.