Gigabyte P55A-UD4 + F3-12800CL8D-4GBRM - no dual channel

[a_lan]

- I put them to slot 1 and 3 and both are visible but this in slot 1 is not active
- I've tried on auto settings and on xmp profile1 (setting is correct according to spec of memory) but still only 2GB active
- I put only one stick in slot 1 or 2, PC didn't start at all
- I put only one stick in slot 3 or 4, PC was working
- I put two sticks in slots 1 and 2, PC didn't start
- I put two sticks in slots 3 and 4, PC was working
- I checked those configurations with DRAM Voltage Auto and 1.6V

1) I would like to run those on 1333 not on 1600. Could anybody write me configuration for that (timings etc.)
2) If not what can I do to run them in dual mode

[GSKILL TECH]

Sounds like the motherboard may be defective if slots 1 or 2 will not work. You will need to send your motherboard in for a new replacement.

Thank you
GSKILL SUPPORT