"Upgrading my computer" questions

[blackstar26]

So I currently have an old HP Compaq dx2450 Microtower which I use for general low performance use. http://h10010.www1.hp.com/wwpc/ca/en/sm/WF06b/12132708-12132884-12132884-12132884-81756671-81756737-81928987.html?dnr=2

However I am now looking at upgrading this system bit by bit to eventually have a new one capable of gaming. Looking at first upgrading case and psu, then gpu ,then motherboard, cpu and a fresh install of windows 7.

So first step being buying a new case and psu and moving all current hardware into the new case ( Antec Nine Hundred which a freind is willing to donate to me) has left me with these questions.
Please forgive my beginner questions, I am quite new to all of this

1) Does a computer case require a certain amount of wattage, if so how much.
2) Will I have compatibility issues with the new case, as it has far more usb's ect then my current one.

 

[unksol]

what you are proposing is a very bad idea. you will not know the PSU you need until you know the other new parts so there is no point in buying one yet. there is no point in a new case unless you are changing hardware and you'd have to install everything twice for no reason the way you are suggesting. If you buy the GPU before the new CPU/ motherboard it will bottleneck. and you'll pay more for less because prices always drop and new parts always come out.

you have a free case, that's good. but you are talking about building a completely new system not upgrading an old one. put the case in a corner, set yourself a budget for a new machine, save until you have it, then select your parts and buy them all at once. I really would not waste time on that HP.

 

[aevm]

Listen to unksol, he's right. Wait until you can afford, say, $800, then post another question and I'm sure somebody will help you pick the parts you need. Keep the old computer as it is, it's good to have a backup that can at least get you on the Internet.

To answer the questions in the original post:

- the wattage you need depends mostly on the graphics card and CPU you will buy. The case itself needs only 20W or so for fans.
- the Antec 900 is excellent for gaming; the only compatibility issue I can see if that your new motherboard will have USB 3 but the case won't; this means you'll need to plug in USB 3 devices in the back of the computer to get the best performance out of them.

Edit: actually, there is an Antec 900 version with USB 3 front ports out there. If you've got that one then good for you...

 

[blackstar26]

Okay that makes alot of sense. The parts I was thinking about getting were-

-CPU: AMD Piledriver FX-4 Quad Core 4300 3.80GHz
- Motherboard: Gigabyte GA-78LMT-USB3 (Socket AM3+) DDR3 Motherboard
- RAM: 8GB DDR3
- Gpu:GeForce GTX 260

What size PSU will I need?

 

[aevm]

500W
http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-260/specifications

Why the GTX 260? There are newer cards out there that do a lot better and consume less electricity. How much would it cost? What country are you in? Maybe we can find you a better deal...

 

[blackstar26]

I live in the Uk and was looking at the 260 because it is recommended for high specs on a fair few of the newly released games. But I am open to suggestions.
Happy to spend anything below £200.