Setsul#923
Have you tried overclocking already? It won't do too much though.
Otherwise either replace CPU+mobo+RAM, use the old parts for another build or sell them as a bundle.
PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i3-6100 3.7GHz Dual-Core Processor ($108.99 @ SuperBiiz)
Motherboard: Gigabyte GA-B150M-D3H Micro ATX LGA1151 Motherboard ($59.99 @ Newegg)
Memory: G.Skill Ripjaws 4 series 8GB (2 x 4GB) DDR4-2400 Memory ($39.99 @ Newegg)
Total: $208.97
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-11-29 17:23 EST-0500
Or, if you're going for as cheap as possible, keep the RAM and go with Haswell.
PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i3-4170 3.7GHz Dual-Core Processor ($104.99 @ B&H)
Motherboard: Asus B85M-G R2.0 Micro ATX LGA1150 Motherboard ($34.99 @ Newegg)
Total: $139.98
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-11-29 17:30 EST-0500
In theory you could go even lower with the G3258 but the budget doesn't call for it and I don't think it'd handle CS:GO well.
how much more performance would i get with the first option?