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FRONTPAGE G.SKill Demos DDR4 4266MHz and DDR4 4311MHz Memory Kits at IDF
- Thread starter Overclockers.com
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- Joined
- Jul 20, 2002
I read a whitepaper article recently that stated that the number of ranks in a DIMM limited the frequency at which it could run. I think the capacity of a DDR module is tied to the number of ranks it has. For some old Westmere-based IBM x3550-M3 servers, full speed, 1600MHz operation was only possible if one DDR3 DIMM was installed per channel. I wonder if this is why they're only offering DIMM's in 2x4GiB configurations.
In my tests so far it's like 2x8GB ( dual rank ) = max ~3466, 1x8GB ( dual rank ) = max 3866, 2x4GB ( single rank ) = max 3733, 1x4GB ( single rank ) = max 4050.
Everything above ~3600 depends in big part from motherboard and IMC. Motherboard manufacturers are guaranteeing work only up to 3200 while everything above is marked as OC ( even though it was tested, they can't guarantee it will work with all available memory kits ). Also almost all 3466+ memory kits tested and approved so far are based on single rank modules ( 2x4 or 4x4GB ).
I just don't think that most 6600K/6700K and most available motherboards can run stable at 4000+.
Everything above ~3600 depends in big part from motherboard and IMC. Motherboard manufacturers are guaranteeing work only up to 3200 while everything above is marked as OC ( even though it was tested, they can't guarantee it will work with all available memory kits ). Also almost all 3466+ memory kits tested and approved so far are based on single rank modules ( 2x4 or 4x4GB ).
I just don't think that most 6600K/6700K and most available motherboards can run stable at 4000+.
- Joined
- Jul 20, 2002
I wonder at what memory frequency the bandwidth/latency exceeds the advantage of having an extra memory channel? For example, does 1 channel of a single rank, 4 GB DIMM @ 4050 MHz. exceed the bandwidth or lower the latency of having two channels of single, rank, 4 GB DIMM's @ 3733 MHz.?
What kind the effect does having the cache/uncore operating at a lower operating frequency than the memory? For example, the limit of the cache/uncore on my i7-5820 is < 3650 MHz (probably because of the Asrock x99 motherboard), if I were running my memory faster than this would my uncore/cache be bottlenecking my memory?
On X99 stock uncore is already bottlenecking DDR4-2133 memory. Whatever people are saying, it's hard to stabilize it above 3500MHz even though you can see 5000MHz in quick benchmarks.
It's hard to compare Z170 to X99 platform. You can reach quad channel ~2666 performance at about 3600 dual channel but only at higher cache frequency and assuming you are comparing 6 core 2011-3 CPU to 4 core 1151. It's more like a theory as on X99 you can set it fully stable while on Z170 on current memory it's barely possible. 8 core i7 will reach higher max memory bandwidth.
There is always some advantage from running memory at higher clock like lower latency so if you can set memory higher then why not.
It's hard to compare Z170 to X99 platform. You can reach quad channel ~2666 performance at about 3600 dual channel but only at higher cache frequency and assuming you are comparing 6 core 2011-3 CPU to 4 core 1151. It's more like a theory as on X99 you can set it fully stable while on Z170 on current memory it's barely possible. 8 core i7 will reach higher max memory bandwidth.
There is always some advantage from running memory at higher clock like lower latency so if you can set memory higher then why not.
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