I thought you are using modded bios. So, please help me with tweakings I use just MSI Afterburner to lower power for GPU and rise memory clocks, 965MHz is rock stable for that Gigabyte, thanks!
You should be able to use the AMDmemory tweak to set the timings in windows. There is a thread only about the utility in this forum.
As for timings happy to share what works for one of mine....every one is a little different but none of my vegas are same batch/model/memory...etc...they are all mutts

ras 26 / rcdrd 12 / rcdwr 12 / rc 38 / rp 12 / rrds 4 / rrdl 5 / rtp 6 / faw 12 / cwl 8 / wtrs 4 /wtrl 9 / wr 13 / ref 24000 / rfc 239
photo linkusing same on both sapphire pulse and getting 50mhs