i3:
PCPartPicker part list:
http://pcpartpicker.com/p/xKsrrH
Price breakdown by merchant: http://pcpartpicker.com/p/xKsrrH/by_merchant/
Benchmarks: http://pcpartpicker.com/p/xKsrrH/benchmarks/
CPU: Intel Core i3-4130 3.4GHz Dual-Core Processor ($118.28 @ OutletPC)
Motherboard: MSI H81M-P33 Micro ATX LGA1150 Motherboard ($49.99 @ Mwave)
Total: $168.27
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-05-28 07:07 EDT-0400)
FX (if you're looking to overclock):
PCPartPicker part list:
http://pcpartpicker.com/p/mv7Bcf
Price breakdown by merchant: http://pcpartpicker.com/p/mv7Bcf/by_merchant/
Benchmarks: http://pcpartpicker.com/p/mv7Bcf/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($117.98 @ SuperBiiz)
Motherboard: Gigabyte GA-970A-UD3P ATX AM3+ Motherboard ($74.99 @ Newegg)
Total: $192.97
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-05-28 07:09 EDT-0400)
FX (if you're not going to overclock):
PCPartPicker part list:
http://pcpartpicker.com/p/J3jgwP
Price breakdown by merchant: http://pcpartpicker.com/p/J3jgwP/by_merchant/
Benchmarks: http://pcpartpicker.com/p/J3jgwP/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($117.98 @ SuperBiiz)
Motherboard: ASRock 970 Pro3 R2.0 ATX AM3+ Motherboard ($59.99 @ Newegg)
Total: $177.97
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-05-28 07:10 EDT-0400)
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Personally I'd take the i3. Also if that 6GB of RAM you have is DDR2 you will need a new set of DDR3.