Seeking help upgrading from MSI Radeon HD5450 to something better for gaming, Budget around +/- $150

[Xi57]

APPROXIMATE PURCHASE DATE: Within the next week hopefully?
BUDGET RANGE: +/- $150, possibly higher, depends on if it's really worth it.
USAGE FROM MOST TO LEAST IMPORTANT: Gaming (Dayz Standalone, Arma 3, etc.), Audio engineering (Ableton, Reason), Streaming.

CURRENT GPU AND POWER SUPPLY: CORSAIR CX-M series CX750M, 750W, 80 PLUS BRONZE - ATX12V & EPS12V Modular PSU

OTHER RELEVANT SYSTEM SPECS: Manufacturer: Systemax
Model: SYX-760GM-E51
Processor: AMD Phenom II X4 965 3.40 GHz
Installed Memory (RAM): 8.00 GB
System type: 64-bit Operating System
Monitor: Samsung 23.6" Widescreen LED Monitor HDMI (S24D590PL)

PREFERRED WEBSITE(S): N/A
COUNTRY OF ORIGIN: USA
PARTS PREFERENCES: Whichever makes transition simpler.
OVERCLOCKING: Idk what this is.
SLI OR CROSSFIRE: Idk what this is either.
MONITOR RESOLUTION: 1920x1080
ADDITIONAL COMMENTS: I'm concerned on whether or not it will fit into my current tower? Ordering something and it not fitting worries me :/

I'd really appreciate your help on figuring out what would be the best option! Again as I said before, I'm concerned on whether or not it will actually fit. If there's any additional info you need on my end let me know. Thanks in advance for the help!

 

[Epicness937]

right now i would get a gtx 950 its near the 150$ price range and will run most games at 1080p medium settings smoothly
your other option is waiting for the r9 470 but in this case its not really worth it.
https://www.amazon.com/dp/B01DOB6S5M/ref=twister_B0144K10RI?_encoding=UTF8&psc=1
https://www.amazon.com/MSI-GTX-950-2GD5-OCV1/dp/B01CX4URJO/ref=sr_1_5?s=pc&ie=UTF8&qid=1466878142&sr=1-5&keywords=gtx+950
these are both good gtx 950s