Low DDR3 2400 MHz write test speed

[lamp_art]

Hi, I have problem with low RAM write speed on AIDA64 benchmark.

My platform is: i5-4690k@4.7 GHz, cache 4.2 GHz Asrock Z87 Extreme3 2x8 GB G. Skill TridentX 2400 CL10 (double sided) Windows 10 Pro

Ram is in double channel configuration with XMP profile active. Before TridentX I had Kingston 1333 CL9 sticks. After upgrade I see massive boost in WinRAR benchmark (~4900 kb/s to almost 7200 kb/s), boost in fps in games, faster rendering and video compression. RAM read tests give me almost 36000 MB/s, but RAM write tests give me only ~21500 MB/s. Shouldn't it be much higher?

I've tried CPU stock clock setting, manual timings configuration, changing RAM 1T/2T and nothing helped.

Motherboard have newest BIOS, Ram are in A2/B2 slots, with slots A1/A2 no difference.

Lowering RAM frequency to 2133/1866 impacts on read speed but write speed doesn't change.

[Fiery]

I think the Memory Write performance is limited by the uncore frequency.  In other words: the memory controller simply cannot churn out more data using non-temporal write, even at higher memory frequencies.