A10-5800K or i5-2500K (In this situation)

Aug 2, 2018
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Hi, I have been putting together a secondary gaming PC and it currently contains:
i5-2500K CPU
8GB Corsair Vengeance DDR3 RAM
Gigabyte Windforce 3X OC GTX 760
ASUS P8BH67-M LE Motherboard
Corsair VS550 PSU

But my Dad has just upgraded his kit and has passed his old system down to me, his contains:
A10-5800K CPU
(I took the RAM, its in my PC now)
Some gigabyte ultra durable motherboard (fm2 socket)
older looking thermaltake 560W PSU

The thing is, I kind of want to use his motherboard since it has 2 graphics card slots and 4 ram slots where my current one only has 2 (so theres potential upgradability) But the motherboard is limited to the A series and a couple of athlons.

The question is would I lose any performance with this change?
Honestly I'm more inclined to go with the fm2 board with the a10 if theres only marginal difference as I feel 8GB will not be sufficient soon...

Thanks!