Suggestions for computer equiptment?

Hey guys, so I'm getting some new RAM, graphics card, and (hopefully not) a new power supply. My budget for all 3 is around $400, and I'd rather not spend over or all of it. I do admit I am a complete computer noob, so if I'd get some good estimates on what I'd need to get in order to get the graphics card I have listed below, that'd be amazing.

I currently cannot check the specs of my currently power supply, but my guess is around 450w.

The graphics card I am leaning towards is the Nvidia GeForce gtx 740. There's been a lot of good reviews for it, but I don't know if I can run it power-wise/processor-wise.

My current processor is the AMD Athlon II X4. 3.00GHz.
Power supply is currently unknown. I'll have to take my computer apart and see for myself, since there is no way of virtually checking.

I wanted to know if I can run the Nvidia card I have listed above, and if I need a new power supply or not. I know it may be tough to figure out if I can run it, since I have supplied no power supply specs. I will do my best to give you guys it some time tomorrow.

Here's the specs for the Nvidia card I'm going to get: http://www.geforce.com/hardware/desktop-gpus/geforce-gt-740/specifications

To be honest, your processor couldnt handle the grapihics card, i have an i3 and i dont run it

What if I changed the processor I was going to get to a Sapphire Radeon R7 240 2GB video card? Could I run that with my current processor?

You would need a faster processor than that, Nvidia graphics are still too fast, i only rin intel graphics 4000

But what about the other one? Sapphire Radeon R7 240 2Gb?

Link me to the info?

http://www.sapphiretech.com/productdetial.asp?pid=E717FBC3-11C2-43E3-A216-291B8BCBC5F4&lang=eng

You gotta scroll down a bit and click 'Specifications'.

I snapped a pic of my power supply. The max it can take is 700watts.

http://imgur.com/fktfzOb

Both of those graphics cards are quite terrible to be honest. You can fit something much better in for 400 dollars, right? Your power supply is probably fine.

How many RAM do you have?

I ordered my 8GB ram (2x4gb) and it should be here tomorrow, Tom. I have already decided that I'm going to check out my current graphics card to see if the ram might boost it's potential. I know it sounds dumb but I don't want to spend another $100+ on something that I may not even need.

This thread does not require any more replies, I'm getting a staff member to lock it.