Where can I find more data comparing the performance of an Intel 750 series ssd (1.2TB HHHL) operating on native PCI-E lanes from the CPU vs PCH supplied lanes. I'll be using a 6700K on a Z170 chipset motherboard. I am trying to determine the penalties caused by the DMI bottleneck, and if it warrants the upgrade to an X99 board.
The DMI 3.0 link between PCH and CPU is equivalent of PCIE 3.0 4x slot. If you don`t use SATA SSD/multiple HDDs, and home network connection is not a Gigabit (or not utilized with more than 100 Mbit/s actual speeds), you have no USB 3.0 storages - performance hit should be negligible in comparison with CPU-provided lanes.
I'm running a video server with multiple 4k streams that is very sensitive to latency spikes, and I'm wondering if the DMI link may introduce performance inconsistencies. I may just have to buy both and test it out.
I find no actual measures of current Intel PCHs latency, but old chipsets some times impose up to 1000 ns delay for PCIE transfers, so yes, you better take a look on X99 platform.
They test out both here (on a samsung drive, not an intel one) :
http://www.myce.com/review/native-z170-hyper-m-2-vs-pcie3-m-2-77791/ Native Z170 Hyper M.2 vs PCIe3 M.2 - Myce.com
and find no difference.