What parts of this computer should I upgrade to improve my gaming experience

[Philosophia]

My cousin purchased a prebuilt computer about a year ago. He is having issues with fps in graphically intensive games which I'm sure you can see why in the build post he gave me. He was thinking of getting a new graphics card and a psu.
He wanted an Intel gpu and I recommended the GeForce gtx 770 with its good performance and low price. He was looking at the gtx 750ti. I explained the features the 770 has over the 750, but I couldn't find any fps comparisons. Does anyone know the performance difference? He also wanted to know how much better the 750ti would be over his current amd r7 250 which I couldn't answer. How much better would the 750 ti be over his current card?
The other part he was looking at was a new psu his current one is a 400w and he wanted a 600w so if anyone knows of a good one that would be a lot of help. Thank you for all of your help.

His pc: http://www.bestbuy.com/site/cyberpowerpc-gamer-ultra-desktop-amd-fx-series-8gb-memory-1tb-hard-drive/9177174.p?id=1218994550644&skuId=9177174

gtx 770: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130946&cm_re=evga_gtx_770-_-14-130-946-_-Product

gtx 750ti: http://www.newegg.com/Product/Product.aspx?Item=N82E16814487024&cm_re=evga_gtx_750-_-14-487-024-_-Product

 

[Aaron Chavez]

Whats your budget?

 

[badboyrog2]

you can compare gtx 750 ti with gtx 770 ...the gtx 770 is far better then 750 ti

and i suggest you the amd gpu instead of nvidia ..because they are cheaper

r9 290 amd series are good and on sale right now

but i do not know the exact hardwares have the cyberpower pc so ...?
check for compatibility and pci-e express

 

[sammy sung]

The 750Ti will definitely out perform the current R7-250, no doubt. However, for not much more in terms of price, I'd look to AMD and side with an R9-280. Much much more performance, for a small price tag. It would however require a power supply upgrade. If he's going to overclock his processor, I suggest one with about 600W and One 6-pin and one 8-pin connector.

The 750 and 770 aren't worth it at this time

PCPartPicker part list / Price breakdown by merchant

Video Card: PowerColor Radeon R9 280 3GB TurboDuo Video Card ($141.00 @ Newegg)
Total: $141.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-11-21 20:52 EST-0500

 

[CreationP]

For the same price and maybe less go for the r9 280x. It's better than the gtx 770.

 

[Philosophia]

Whats your budget?

He said his budget for the graphics card was $200-300 that's why I recommended the gtx 770. I think that range he gave me is on the extreme end and that he isn't completely comfortable with it that's why I asked these other questions.

 

[Philosophia]

you can compare gtx 750 ti with gtx 770 ...the gtx 770 is far better then 750 ti

and i suggest you the amd gpu instead of nvidia ..because they are cheaper

r9 290 amd series are good and on sale right now

but i do not know the exact hardwares have the cyberpower pc so ...?
check for compatibility and pci-e express

The 750Ti will definitely out perform the current R7-250, no doubt. However, for not much more in terms of price, I'd look to AMD and side with an R9-280. Much much more performance, for a small price tag. It would however require a power supply upgrade. If he's going to overclock his processor, I suggest one with about 600W and One 6-pin and one 8-pin connector.

The 750 and 770 aren't worth it at this time

PCPartPicker part list / Price breakdown by merchant

Video Card: PowerColor Radeon R9 280 3GB TurboDuo Video Card ($141.00 @ Newegg)
Total: $141.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-11-21 20:52 EST-0500

What would you recommend as a power supply?

 

[badboyrog2]

corsair cs 750m gold rated

 

[CreationP]

A minimum of 600-650 watt PSU.

 

[Philosophia]

For the same price and maybe less go for the r9 280x. It's better than the gtx 770.

I don't know much about amd cards. How much better is the r9 280x over the 280?

 

[CreationP]

The 280x is faster than 280.

http://www.hwcompare.com/17659/radeon-r9-280-vs-radeon-r9-280x/
http://gpuboss.com/gpus/Radeon-R9-280X-vs-Radeon-R9-280

 

[Philosophia]

The 280x is faster than 280.

http://www.hwcompare.com/17659/radeon-r9-280-vs-radeon-r9-280x/
http://gpuboss.com/gpus/Radeon-R9-280X-vs-Radeon-R9-280

I haven't gone over to his house to check out the pc in person, and I don't know what cooler is in the pc, How hot does the 280x get?

 

[badboyrog2]

r9 280x = 90 degrees max , amd gpu are fu....hot