[james62755]

i have a Compaq Presario SR1630NX Desktop PC and i want to put in graphic card but i requires me to upgrade my power supply i currently have this model running my power an ATX-300-12Z Rev:.BD 300W would a 550W 3X SATA PS for BESTEC ATX-300-12Z PSU Rev.: BC fit in good and be safe on my system?

[leroys1000]

Try to stay away from brands like bestec.
Get a decent power supply from antec,ocz,corsair or
something similar.
The power supply is the foundation of the computer.
Don't want to use something cheap and take a chance on
trashing your computer.

[crashie]

Make sure the PSU is a reputable brand - a cheap one won't push out the correct voltages and you won't get its full rating.

[james62755]

so whats a good for the watts out put or does it matter as look as the graphics card or any thing i put on it meets the watts requirement?

[Mosquito555]

First of all you must check if a new PSU will fit in your case. It's not unusual for OEMs to built machines with specific dimensions.

Assuming that your case has standard ATX dimensions you will have to consider these things:

1) The Wattage of the PSU.

2) The Amperage rating of the +12V rail(s) of the PSU.

Modern processors and graphics cards rely on these +12V rails to get the power they need. If these rails can't provide enough current then you may experience random restarts and instability while stressing your computer (for example while gaming). It's possible that your computer won't start at all or even get damaged if the PSU isn't good.

Modern PSUs usually have multiple +12V rails. IMHO, you should get a unit that has at least three +12V rails which can provide at least 18 amperes.

High end PSUs usually come with only one high current +12V rail (which usually can provide more than 40 amperes). That's a better approach for several reasons but these units are more expensive.

The guys who posted above me gave you some good advice regarding PSU brands. Now, the question is, what graphics card are you planning to buy?

Give us more details regarding your machine (CPU, memory type and amount, number of drives and fans etc).

For a med end graphics card you can get something like this:

http://www.newegg.com/Product/Produc...-031-_-Product

For a high end graphics card or if you want to ensure that the PSU will be enough for future upgrades you can get:

http://www.newegg.com/Product/Produc...=corsair%20550

http://www.newegg.com/Product/Produc...-005-_-Product