i7 3820 vs i7 4790 Performance gap?

[Overside]

Hi,
So I was going to build a new rig on the z97 platform with the 4790k processor (Haven't bought anything yet). However my friend has just moved from his x79 system to x99 and is willing to sell me his sabertooth x79 mobo + i7 3820 processor. He claims that the i7 3820 can be overclocked to 4.675 GHz easily. My question is that how close are these two CPUs in performance? at stock versus both OC'ed? any advantage the x79 chipset has over the z97 or vice versa? It would be cheaper for me to buy his mobo+CPU but if the i7 4790K is significantly faster that's still what I will be getting.

 

[blazorthon]

They're pretty equal. That X79 system would serve you well.

 

[geofelt]

The I7-3820 is an older sandy bridge architecture which is not as capable, clock for clock as haswell i7-4790K.
I would go with 4790K which runs 4.0/4.4 stock.

That said, I would wait a bit for the next gen Skylake, due in august.

 

[blazorthon]

The difference is at worst around 15% or 20% and with the extra cache and memory bandwidth on the 3820, it's a little smaller of a difference than like with the i7-2600K or 2700K. If he's getting it for cheap, then it's certainly worth it and he might not be able to wait for Skylake with his friend. I suppose that it's worth asking. Skylake might increase the difference, it might not, but if the price is right, it doesn't matter.

 

[martinch]

IIRC, the quad channel memory X79 uses should have more bandwidth (by a factor of 2), although IIRC the Z97 CPU can use faster memory which will go a way to offsetting this. The Haswell CPU has 2 generations of architectural improvements, including additional integer units and instruction support, and clock-for-clock will be 10-20% faster (although the Sandy Bridge-E has more cache). Overall, I would expect performance to be roughly similar, with the 4790K having an edge, dependent upon workload. Both should be more than adequate.

A further consideration is the Z97 has fuller support for USB 3, PCI-E 3 (motherboard dependent), SATA 3, SATA-Express and M.2.

 

[Forever Oleg]

Honestly there is minimal difference between the two with the i7 3820 being 10% slower. Go for whatever is cheaper