I'm gona be building my first PC. I have a 200w old PSU is this enough to power it. Also, I know this is a really noob question, but are the cables interchangeable? (power and ATA)

400W would be nice(depends on system).Power cables and ATA connectors are not interchangeable.

As Peddant said 400W will be nice but 200W also will work for basic configuration.

You may want to check the link below that is a table which shows computer items and watts they use:

http://computer.howstuffworks.com/power-supply3.htm

http://www.pcpowercooling.com/technology/power_usage/

For better understanding of PSUs, i suggest you to read whole article. By looking at the table there, you can figure out what PSU you will need.

200W is not enough to power todays systems I'd say.

Let me rephrase my question about the cables being interchangeable. I meant can the same cable that goes to the CD drive just be switched to the hard drive.

Two more questions:

Can you tell me what the P and a number means on each of the power cables.

Is there any way I could burn out a part by plugging in the wrong power cable. I know that different parts have different cables but could a power supply be too strong for a something and burn it out?

I guess I will need a new power suply after seeing the chart. Thanks for your help.

If you put the words "building computer" into google,you`ll find at least 10 zillion how to sites.That`s the best way to find out those sort of things.

Because the internal electrical connectors are different, it would be hard to plug in the wrong thing. If it doesn't belong, it won't fit.

You are right about the cable for the hard drive and optical drive. If they are both IDE devices, they use the same type of cable. They can be on the same cable even. The exception would be if the hard drive is the newer serial ata (SATA) hard drive. SATA uses a different cable and connects to a different controller on the motherboard. But the connectors are very different and you can't confuse them.

Thanks mailpup. That’s what I thought.

So when working with the electrical cables if it fits, it works?

Yes. BTW, let me clarify a bit. I kind of mixed up the discussion of electrical power cables with data cables but either way the connectors are different anyway.

I went out and got a 300w psu. I think this will be enough. I'm only planning to have a basic system configuration.

Here are some more stupid questions:

I went out and bought the mobo before the case because I am buying the case online and I bought the mobo in a store. The mobo did not come with screws so I was wondering if they usually come with the case. Also, how do you keep to mobo from touching the case so it does not short out?

You'll get a load of fixings and stand-offs (these space the mobo away from the case).