Need new PSU for Alienware X51 R1

[KartikeyaD]

Hi, I own an Alienware X51 R1 which I bought in May 2013.
So, I had a problem with my graphics card, which was Dell GeForce GTX 660, and after contacting Dell and confirming the problem, they sent a replacement graphics card along with the engineer.
Now, instead of sending a GeForce GTX 660, which was the stock graphics card to have come with the CPU, they sent me a GTX 760. I didn't know if it was a mistake or not, but knowing that it was a better card and that there might be a chance of it fitting in the chassis, I let the engineer replace the card. And the card fit in perfectly. I have been trying all recent games and they are working extremely smooth.
I know that the card needs more power. And the CPU has an external 330 watt power supply, that is, the PSU is located outside. So now my question is,
Should I change the PSU?
I mean should I give it a bigger power supply? If yes, then which power supply would you suggest me? (I would crave links)
Or is it that I cannot change the PSU as the motherboard would be incompatible it?
My current CPU Specifications are:-

Intel® Core™ I7-3770 Processor
SandyBridge (8MB Cache, up to 3.80GHz)
Intel® H61 Express Chipset
8GB RAM
nVIDIA® Geforce™ GTX 760

Pls hlp I give u cookie.

 

[DHFF]

I have never heard of an external power supply. is that the only source of power for the computer or is that a power supply dedicated to the CPU, with the rest of the computer having an additional power supply?

 

[KartikeyaD]

Here is the link. It lies outside, that's what I meant. And Its dedicated to the CPU only.
gyazo.com/670602f57d1f1d19e24ea5d3fd4f3b3c

 

[DHFF]

That is so bizzar. I can honestly say in 20 years I have never heard of a setup like that. I assume you have a standard power supply feeding the rest of the rig? can I get the specs on that? I have no idea why Dell would have two separate power supplies.

 

[KartikeyaD]

I'm sorry, The PSU is a brick. I thought it was as easy as just replacing the 330w brick with a better one.
I guess it can't be changed. Damn.

 

[sarcophagus_macabre]

You should be fine. The GTX760 is a newer version of the 660 you had before, and Dell should know what parts they can put in their machine.

 

[KartikeyaD]

I know. I so wanted to overclock this one. Thanks by the way.