Iknow iwill change it if worth upgradedThe i5-2400 and e5-2689 are completely different sockets.
I was thinking this would be a good route as well, especially if the lga2011 won't support the v4 2689:Find out what your mainboard supports...
Look at prices of I7-2600/2600K, compare to any compatible equivalent Xeon...(which gives no greater perfomrance than the i7 at the same clock speeds, so, no need to expend great effort searching for one if you can find a normal i7)
I'd be hesitant to sink much more than $30 for one, as the current AMazon asking prices for a 2600K at $100-$120 are ridiculous, as that perilously close to R5-2600 prices....and $40 above an R5-1600's prices.