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$200-$250 computer build. all all the parts compatible, any issues you see?

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here are the parts for my first build. please tell me if you see a problem with the selection

CASE: ------Cooler Master RC-343-KKN1
MOBO:------ASRock Z77 Pro3 LGA 1155 Intel Z77
(any better value out there)?
CPU: --------Pentium G620 (lga-1155) (can you best it within  $60?) (stock)
GPU:---------n/a, on-board Intel HD 2000
RAM:--------Team Elite 4GB 240-Pin DDR3 SDRAM DDR3 1333MHz
OS: ----------Ubuntu 12.04 LTS 64 bit.
HHD: --------the old HDD i have in my old computer, a 250gb 5400RPM drive.
OPTICAL: -my current DVD drive in my old computer.
PSU: --------will 350W be enough power for this? i think so.

[total cost]: <$250 including the parts i don't think i need. (optical, case, PSU, CPU, heatsink)

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IF YOU SEE EVERYTHING IS GOOD AND COMPATIBLE AND ANSWER THE QUESTIONS, YOU GET BEST ANSWER.

other questions:

1) what advantages can i get out of a good housing/case? can i get more USB ports? or are the aftermarket cases just for looks and good airflow?

2) my current hard drive is loud (no clunking, but clearly audible clicking (30 decibles maybe?) and some faint brown noise under load). it is an older heavily used HHD, how much life does it have left? i don't know of any software to test it. i use Ubuntu as my only OS so a program to test it has to be for Linux (preferably .deb package)

i have more info and qustions at:
https://www.instructables.com/answers/ultra-budget-computer-system-with-good-upgrade-opt/

if you could also answer those, i would highly appreciate it.