help with mobo upgrades or swap ddr2 vs ddr3 for vid editing

[Fishheads IV]

i have a computer with G-p3G-p35 -dsr2 board and 4gig of 800hz xlr8 (2×-2gig) sticks. id really like to get to 16g for editing

Should i expand to 8gig and if so can i mix and match with less expensive board

Or how hard / expensive would it be to swap the board for a decent one that takes ddr3 up to 16gigs

 

[damric]

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Xeon E3-1231 V3 3.4GHz Quad-Core Processor ($231.99 @ SuperBiiz)
Motherboard: ASRock H97 PERFORMANCE ATX LGA1150 Motherboard ($79.99 @ Newegg)
Memory: G.Skill Ares Series 16GB (2 x 8GB) DDR3-1600 Memory ($97.99 @ Newegg)
Total: $409.97
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-04-29 00:20 EDT-0400

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i7-5820K 3.3GHz 6-Core Processor ($362.95 @ SuperBiiz)
Motherboard: MSI X99S SLI Plus ATX LGA2011-3 Motherboard ($149.99 @ SuperBiiz)
Memory: Crucial 16GB (4 x 4GB) DDR4-2133 Memory ($149.99 @ Newegg)
Total: $662.93
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-04-29 00:23 EDT-0400