Keeping the stock PSU and Stock CPU, and upgrading with an HD7770 without replacing the power supply you have a good ($530 plus $125) = $655 system. 80W HD7770 uses low enough power so would run on stock 300W PSU with 65W i3-2120, but would not be as fast as GTX560 you spec'd.
Replacing the stock PSU with an antec VP-450 (good reviews, $40) plus gtx 560 graphics card 2gb - $150 gives you a nice $530+$40+$150= $720 i3 based system.
I'd stop with one of the above systems, however if you have another $200 burning a hole in your pocket spending $200 for an i5 CPU would not be the best way to spend money on a gaming system, instead stepping up to a better graphics card would give you better balance. Here is one of many good refs: http://www.tomshardware.com/reviews/gaming-graphics-car...
If you want to spend another $200 (and your goal is gaming) don't get the GTX560, instead get a GTX660ti or HD7870 or HD7950 and keep the i3.
i3+ gtx660Ti = $300 upgrade
i3+ hd7870 = $300 upgrade (price will fall now that gtx660ti is shipping to $275?)
i3+ hd7950 = $320-$350 upgrade (prices is adjusting for gtx660ti too, plus HD 7950B)
i5+ gtx560 = $340 upgrade
For gaming, any of the i3 three builds above would be stronger than the i5 build.
Thank you, i really love the idea of just keeping the i3 (saves money) and also do you know how much watts i would need with the gtx660ti, or actually if the gtx 560 will play like battlefield 3 on atleast medium to high? i'm not really picky about the setting as long as it is just above medium on most games with atleast 50-60 fps or a minimum of 40 fps. This would be my first gaming system and i have done a whole lot of research too.
would this be worth keeping and in the future buying a new mobo and everything (4 to 5 years from now) and just basically redoing everything later on without having to go on a huge search for the cheapes cases and all that?
if the gtx 560 will play all the games i want with 50-60 fps just above medium graphics then that is all i ask for (i'm not picky i can always upgrade later and that is all i'm looking for is a computer that i can continue to play for a while now and then upgrade in the future)
I am looking to play most of the popular and well known games and mmo's alike and i know alot of them require alot of power.
I really do appreciate your help here it is saving me time and worry and if i can decide on the gtx660ti vs gtx 560 then i will be done and go get them
ok thank you, so with that graphics card i will not need to get a new psu right?
Yes, you can run the Hd7770 on the stock 300W power supply in the system you referenced along with an i3-2120 CPU and rest of computer.
The Hd7770 is a simple install. It needs one 6-pin PCIe power lead attached, then you push it into the x16 slot. If you later have to remove it all x16 PCIe slots has a catch at the back end of the slot to hold the video card in place. Take a good look at the catch to see how you open it later to remove the card. Its hard to see once the card is installed. Typically you push a plastic part to the side with you finger while lifting teh card. Sometimes people tug on the card without releasing the catch -- that's bad.
For the 6-pin PCIe power lead you need... Your PCs power supply will have a number of unused power cables bundled up and zip-tied. You cut the zip tie and they all fall down. If there is a 6-pin connector there use it. If not then you need to get an adapter. This is a common enough need that many video cards bundle MOLEX (lp4) to 6-pin PCIe adapters. The description of your video card will say if it comes with an adapter. If not, this is a $5 part. Here is a link to an adapter. It has nice photos so you can see what a 6-pin looks like and what a molex looks like if you don't know already. http://www.newegg.com/Product/Product.aspx?Item=N82E168... The only nice thing about using the adapter is that it gives you another 6 inches of power leads, which sometimes makes routing the wires easier. (Aside: I've used these adapters 3 times now. Someone pointed out to me that you can also adapt a SATA power adapter to 6-pin PCIe. That looks good if you have spare SATA connectors on your PSU. Here is a Sata to 6-pin PCIe adapter: http://www.amazon.com/StarTech-com-SATPCIEXADAP-6-Inch-... most PSUs used to have more molex(lp4) then sata, this should be changing over time to having more sata.)
Some background on power consumption.
The HD770 draws 80w max, and even overclocked will not allow more than 100w power before it throttles internally to prevent damage. You can find both these numbers by (1) googling HD7770 and TDP. This will give you thermal design power = 80w for the card. The card typically run less but you need to plan for 80w. (2) goggling hd7770 and power tune limit. Tht will show the hard 100w cap.
Here is an article that gives TOTAL system power for a config running an HD7770. Note this config sports "Intel Core i7-3960X @ 4.3GHz" which at stock frequency has a max wattage of 130 W vs. 65W for the i3. The i7-3960 is also running overclocked which adds wattage, and yet the highest loaded game with the HD7770 total system power consumption was 250W at the wall, or (with 80% power supply efficiency) 250 times 0.8 = 200W power supply output. That should give you comfort you have headroom with a 300W psu. http://www.anandtech.com/show/5541/amd-radeon-hd-7750-r...
I think you were going to buy the system, but had not purchased it yet. If so please double check the reference that shows a 300W power supply. If you already have the system, open case and check PSU output... it's usually visible on a yellow sticker on the power supply. If for some reason you didn't have a 300W PSU then the analysis above fails. Otherwise you are good.
If you order an Hd7770 and run it with the stock 300W PSU can you update this thread so people can see it works.