Samsung 840 Pro Poor Performance

I get really poor write and 4K performance with my 840 Pro 256GB. 
System specs:
4770K @4.3GHz 1.25v
Maximus VI Formula Latest 6/8/2013 no.0804 BIOS
Kingston HyperX Beast 8GB 2400MHz @2400MHz
Corsair TX750M
Sapphire HD7950 VaporX oced (1000/1300)
Samsung 840 Pro
Seagate 7200.14 2TB
Swiftech H320
Corsair 900D

The SSD is the boot drive and is relatively new (1.67 TB written). I performed a secure erase when I got my new computer through the UEFI of the Formula and installed windows 8 (I was using it in an older system with windows 7). I overclocked and had some bluescreens but I checked the disk and windows is not corrupted. The disk is plugged in the Intel port, not the 3rd party controller. I have 164 GB of free disk space. 

Firmware: DXM05B0Q 

Screenshot of CrystalDiskMark and CrystalDiskInfo:

Please Help!

Those write speeds are shiiite, tried updating the firmware? Run off another non-intel sata port?

here is my speeds on the same drive as you;

I would probably just rma it anyway.

For some reason it just went back to normal today (without any updates on software/drivers)

well i can tell you i have the 120GB version 530 read and 390 write, but the speeds on the box it just don´t reach it.

I had the same strange thing, wiered numbers, and i tried also everything. after a few days of arguing couple of windows reinstalling  i got now reasonble numbers.


yeah i have the ocz vector 128gb version and it doesnt reach its read and writes it says, but there very close, what version do you have? usually the smaller drives are a bit slower

Ive got the Samsung 840 128GB pro. 530MB/s read 390MB/s write, so i think my numbers are nice ☺