But how is 4000 cl18 docp working for me think. Also I'm able to get 4000 manually too with 1.425v without timings though.the problem is when I'm putting dram calculator settings.basically I'm able to run 3600 but as soon as I change timing, can't boot, how to tighten timings then?
If you are able to get 3600, I'd call it done. Going above that is getting close to actually decreasing performance due changing IF speed.
Just first make certain it's stable...that DRAM Calculator has a memtest feature to help with it. Test each to 200% on 'single', it takes a while but if it passes then you'll know you're good to go with confidence!
Oh yes...and try lowering voltages a step at a time until it either refuses to start or fails a memtest. Lowering volts help keep it around a bit longer but you can leave it there while you test for lowered timings.
Playing with timings is a time-intensive trial and error process. Start with just the primary timings, tCL, tRCDWR, tRCDRD, tRP, tTRAS, tRC...reduce this one notch at a time and try. tRC should always be equal to or greater than (tRAS + tRP). Also reduce tRFC, it can be change 10-20 at a time since it has a wide range.
Only consider it good if it passes a full-on memtest, 200% for each thread. If it fails a memtest, up the voltage a notch and try again. If it then passes you'll then have decisions to make.
That's really all I'd try and any benefit will be very hard to notice, probably not really worth the effort actually as leaving timing margin will save your bacon as components age. And the higher the voltage you run with, the sooner they'll age. Meaning stability problems will arise with time so you have to go back through this again.
Oh yeah...even if you use no other DRAM Calculator settings DO use the ProcODT (or alternates), setting. It's not a timing change and won't improve any performance, but getting that right has the greatest potential to assure reliable boots at elevated clocks.