i7 or i5 (gen 6 and 7 skylake and kabylake) for mini ITX with 2 RAM slots?

[kutneuker]

hi,
when I compare specs on wikipedia of i5 and i7 I can see that some i7 can handle 8 DIMMS of RAM and as my Asus Z170i pro gaming mobo only has 2 slots I wonder if that's just a waste?
Not interested into 'K' variants as I never overclock (unless the mobo does so with its AI automatic overclock feature which is not entirely clear to me as to what it refers: real overclock or just turbo boost?)
Also planning to use SSD on its M2 pci slot and only 1 GPU, does the number of supported pci lanes matter? Don't need answers about cost (not that I'm rich) as these drop all the time, this post is about specs.
If anybody has the same mobo with M2 SSD feel free to share experience, thx to all ;-)

 

[TJ Hooker]

Z170 motherboards are socket LGA 1151. There are no LGA 1151 i7s that support 8 DIMMs (those i7s require LGA 2011 motherboards).

The AI auto overclock is a real overclock, it just attempts to increase the frequency and pick an appropriate voltage for you. You still need a -K CPU for that.

For 1 GPU and an M.2 SSD, PCIe lane count doesn't really matter. Also, all CPUs that you could use with that mobo have the same number of lanes anyway.

 

[kutneuker]

hi, thx for the short precise answer.
So besides the bit higher clock on the i7 6700K (4.0) and i7 7700K (4.2GHz) or i5 6600K (3.5) and i5 7600K (3.8GHz), does it make sense to put an i7 instead of i5 in a mini ITX? Don't care about the integrated graphics.
Also on wiki it says the i7 cpu only supports 16 pci lanes (well, it's that for skylake, kaby is not mentioned), I thought it was already 28 or 40 and that that was the point of the latest cpu's.
In pci 16x port, the GPU already uses 16 lanes, so combining this with extra pci lanes used on M2 pci SSD will slow things down or am I wrong regarding this lane use count?
Thx Adept ^o^

 

[TJ Hooker]

The i7s that have 28 or 40 lanes are the ones on LGA 2011.

i7s have hyperthreading, so they have 8 threads instead of 4 like an i5. Some games and applications benefit from this, some not so much.

In addition to the PCIe lanes direct from the CPU, there are additional lanes through the motherboard PCH, which are separate. So your graphics card will use the 16 from the CPU, the M.2 SSD will use ones from the PCH and won't interfere.

 

[kutneuker]

Hi yes, hyperthreading. As previously (back in the day) when stepped up from 2 to 4 cores it's not easy to find a list of programs or applications which clearly state how they spread the workload to know which design suits them best (how many cores and threads suit best).

Not sure what motherboard PCH is (did you mean PCB?), will look it up.
A major question I was asking myself starting this thread was the effect of the small number of RAM lanes on mini itx as I didn't find so much info regarding that.
From your answer (and the fact that the number of ram lanes is rarely mentioned in other threads) I guess it might not be so important? And performance might be more determined by the chipset? (besides obvious things like cpu, ssd etc)
Sorry for all the questions but I couldn't find an answer to them in all the comparisons and benchmarks I read in the last 2 years (and some sound more like a sales pitch than actual info).
thx TJ ;-)

 

[TJ Hooker]

4 vs 2 RAM slots has no impact on performance. It just limits your maximum RAM from 64 GB to 32 GB.

PCH = Platform Controller Hub.

I wouldn't say chipset has much impact on performance directly, moreso it impacts which features and # of connectors a board will have.

 

[p5yc0k1ll3r]

I have an i7 7700 non k on a msi b250m bazooka motherboard with 2x8ddr4 2400mhz gskill ram sticks and an Rx480 4gb. It literally 3fps slower than an i7 7700k un battlefield 1. Even an overclocked i7 7700k gaines maybe just 1 fps extra. So yea go for a non k variant. They are the same without a big price to pay. Sorry if i didn't give more info on other things that you wanted