PC will not start MSI GTX 550 Ti

[Krond]

I bought an MSI Nvidia GTX 550 Ti about a week ago, and just got it yesterday. (Bought from Tiger Direct, found here: http://preview.tinyurl.com/an8matd ). When I install it in my PC, when I turn it on, it begins to start up but shuts off after a few seconds without anything coming up on screen.

Here are my system specs:

-Intel Pentium D 820
-MSI G41M4-F
-500w PSU (Not sure exactly what it is called)
-4gb RAM
-Windows 7 64-bit
-1TB Hard Drive
-Original case from the Acer Aspire T671 (I believe that is the model number)

I could use any help possible.

 

[mc_creeper]

Please find out what PSU you have as that is most likely the problem. Make sure that all of the connectors are correctly connected.

 

[Krond]

I'll have to get back to you on that, currently not at home.

 

[Krond]

I got it to work so far, actually. I completely forgot about the cables that came with it to hook it up to the PSU. Silly me.

 

[Krond]

Well... After using it for a short while I started to smell something. My PSU started to overheat. I had to remove the card and put in my old one. So, my PSU is weak and I need a new one. Does anyone know of a PSU that would be powerful enough for this video card but can fit in my case? It's the case of an Acer Aspire T671.

EDIT: Also, I have an additional problem with my ATi Radeon HD 6670, which is the card I am upgrading from. When I have the GPU clock at the default 800 MHz, and begin playing a game, the drivers crash and recover a few seconds later. It works fine at 700 MHz, but I get less FPS. I use the 12.10 drivers, which are the most recent (10/22/2012).

 

[Thenumber16]

I think PSUs only come in one standard size, so any should work. The geforce website says you need at least 400w, but you should probably think about getting a 500w one to be on the safe side. Look around and check reviews to ensure quality before buying, and if in doubt about whether it'll fit inside your pc you can always try measuring it!

Take a look at this for ideas on reputable brands:
http://www.tomshardware.co.uk/forum/261795-10-makes-power-supply