GPU upgrade for my current PC...

[mwwwilson]

I'm looking to upgrade, if at all possible, my graphics for gaming for Christmas. I am wondering what would be the best bang for my buck? I'm not upgrading anything else in this PC, except for RAM. This is what I have:
MOBO=Biostar A770E3 (can accept a one PCI Express 2.0 x16 card)
CPU=AMD Phenom II x4 840
RAM=Mushkin Silverline 2x2 GB , but this is about to be
CORSAIR DOMINATOR GT 8GB (2 x 4GB)
PSU=RaidMax Hybrid 2 530W

Current GPU is a ZOTAC AMP GeForce GTX 550 Ti 1GB

Wanting to upgrade for optimal settings and framerate increased. The problem is I don't know where my limit is on a GPU with my current setup. Again... I am not going to upgrade anything else. So please just suggest a card that will suit my current equipment. Take into consideration the RAM upgrade though because that is happening in a week.

I know that a some point my CPU and PSU will slow down a GPU. I just don't know what that max is. I know that I can do better than the GPU that I currently have. 660 ti??? or can I sneak a little more power & performance out of another card?

As always, Thanks in advance. All you guys are great to me. Top notch advisers and troubleshooters.
Thanks,
Mark W.

 

[PP Mguire]

At some point your PSU could completely kill your whole system. I would worry more about upgrading that first rather than doing anything else. Raidmax and Apevia make some of the worst bottom of the barrel cheap units to date.

I also wouldn't be wasting money on top end RAM like that either. Basic 1600MHz DDR3 is all you need for any rig.

To answer your question, R9 270x really. Can't go much higher.

 

[mwwwilson]

Any particular maker of that GPU?
Also, what PSU would you suggest?
Thanks

 

[PP Mguire]

Depends on your budget honestly.

You could get a lower wattage Seasonic like this which would handle most any single GPU setup and it's modular. The non-modular one is 10 bucks cheaper.
SeaSonic M12II 520 Bronze 520W ATX12V v2.3 / EPS 12V v2.91 SLI Ready 80 PLUS BRONZE Certified Modular Active PFC Power Supply - Newegg.com

For brand on the 270x, XFX, Asus, or Sapphire. If you have a higher budget and can get that PSU I would go with a 760 or the 280x.