Please help

Okay so you have a regular profile slot configuration I took a look here.
http://www.dell.com/us/dfb/p/optiplex-760/pd

Your power supply is very very small. If you upgraded that you could probably handle more. If you upgraded your power supply I would suggest nothing higher then a 650ti or 7770. On the other hand if you stick with your current Power supply nothing higher then a 610 as the minimum system requirements even for this graphics card are suggested at 300 watts which is as low as you will see.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

i can get a new psu if needed

i can get another psu if needed

If you feel comfortable with installing a power supply I would suggest something like this. The power supply isn't very large and should be able to be housed within your case.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

In terms of graphic cards then I would look towards. IF you want to be more on the gaming side of things maybe do some medium mixed with high settings then go with the 650Ti, if you want to enjoy some light gaming then go with the 650. The better value is in the Ti but your budget in consideration may feel otherwise.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
or
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Also a 7770 may be a valid option as well.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Just something to keep in mind the higher up you go graphically the more your system is going to pull you down to earth as you will hit a brick wall. Your CPU is rather slow compared to what the GPU's today need to power them. Lower/Mid range cards are probably the best area for you.

im just trying be able to run games intill i can get another motherboard/cpu

Well then I would say the 650Ti would be as high as you should go and what I would tell you to get. What kind of settings would you prefer to be at? (what you deem acceptable)

enough to start the game becouse without a dedicated video card, because some games you need one

You could start a game with a 650 and play reasonably well with toned down settings quite a bit you can turn up settings a bit more with a 650Ti not maxed out settings but pretty decent this goes for modern games older games more then likely pretty close to maxed out.

Would this graphics card work for hp p6674y desktop

Granted you upgraded your power supply yes.

I just found out that the motherboard is fried. Do have any suggestions on buying another that I can buy in a store. Preferably best buy. I bought a 520 watt psu

How do you know that your motherboard is fried? Also, I'm not sure the size of your motherboard some of these companies do proprietary things with there computers Dell being a main contributor.

When I try to turn it on the mobo light and fan turns on, but nothing happens after that. No beep no display

It's not the psu because I just bought it and did it to old one too. The case is either a mid tower or ful

This topic has been closed by Mousemonkey