Well I did say its per core performance was better, not its overall performance, I was also factoring over clocking (the i5 will have ~ the same performance per core as an FX clocked ~1GHz higher according to Anandtech benches).
What if you got a secondhand FX6300,then?? If they cost £100 new,then they probably will cost a decent amount less as more secondhand ones hit the market.
Moreover,with the FX6350 being released,I suspect the FX6300 will drop in price too which will also affect secondhand values. Like I said it goes both ways.
Look at the Crysis 3 benchmarks again. In the most intensive part of the game the 3.5GHZ FX6300,has a 28% increase in minimum framerates and a 19% increase in average framerates over a 2.8GHZ Core i5 760.
It does not matter in this case,if the Core i5 760 has potentially faster cores,as the FX6300 overclocks a decent amount,is brand new and has more up to date motherboards too.
On top of this the Core i5 700 series has old instruction set support,which is another black mark against them. Moreover,even the SATA3 controllers(which not all P55 motherboards had),were third party too.
Most socket 1156,motherboards will be years old now,and that alone would put me off recommending it as a "new" platform for a new PC.
You also have no clue how many volts have been pushed through the secondhand CPUs either. This is more an issue with older CPUs. There are people who end up pushing the overclocks on such CPUs,and then finding that over time,they need to keeping slightly pushing the volts up due to EM problems to maintain the overclocks. How do you know whether they are palming off a knackered CPU like that then??
OTH,you might get a CPU which has never been overclocked and has had a very comfortable life.
Its a lottery. This is why people need to know the risks,and considering a lot of people on forums asking for build advice,have not much experience with building PCs,I would err on the side of caution as I am spending their money. They might want to keep the system for the next three to four years even.
They are only really useful as a cheap update to an old computer running a socket 1155 Core i3 or Pentium dual core.
CryEngine 3,id Tech 5 and Frostbite 2.0,all do well on a FX6300 for a £100 CPU. It is most likely UE4 will do the same,as even UE3 can use 4 threads effectively. Those are the big 4 engines which will define many games in the 4 years alone.
What I am interested to see,is if Haswell improves HT further or not.