Any tips & tricks for overcoming the RAM speed wall on Haswell-E/X99?

[steffeeh]

X99 and Haswell-E is known to have RAM compability issues between 2800-3000/3200MHz, on which Broadwell-E significantly improved by improving the CPU IMC.
However I'm on Haswell-E, and while my RAM kit config is 1DPC which is preferrable for Haswell-E, the RAM sticks are built with dual rank which is less preferrable with this architecture.

I've managed to overclock the memory to 2666MHz 13-15-15-28 stable so far (very good imo!), but I can't for all the love in the world make the BIOS even post at 2800MHz. In the past it could post here with just one stick being detected, but I guess newer BIOS versions only posts if it can connect with all sticks.

I've tried setting the following voltages; 1.4V vDIMM with VTTDDR at auto, VCCSA/SystemAgent at 1.15V, and VCCIO at 1.15V - no post.
I've even tried giving generous latency as a failsafe, up to CL18 with adjusted other primary timings mimicing Corsair XMP profiles from other kits.
I've also tried loosening the tertiary _DR -timings (the few I could find in BIOS) which should go easier on the IMC, but without luck.

My relevant system specs:
- Motherboard/Chipset/BIOS: Asus X99-A, American Megatrends, version 3402 (not using the latest one 3505 as it screwed everything up and I had to revert back)
- CPU: i7 5820k (Haswell-E)
- RAM: 2x 8GB (=16GB) Corsair Vengeance 2400MHz 14-16-16-31, dual rank, dual channel/1DPC

 

[Vellinious]

X99 and Haswell-E is known to have RAM compability issues between 2800-3000/3200MHz, on which Broadwell-E significantly improved by improving the CPU IMC.
However I'm on Haswell-E, and while my RAM kit config is 1DPC which is preferrable for Haswell-E, the RAM sticks are built with dual rank which is less preferrable with this architecture.

I've managed to overclock the memory to 2666MHz 13-15-15-28 stable so far (very good imo!), but I can't for all the love in the world make the BIOS even post at 2800MHz. In the past it could post here with just one stick being detected, but I guess newer BIOS versions only posts if it can connect with all sticks.

I've tried setting the following voltages; 1.4V vDIMM with VTTDDR at auto, VCCSA/SystemAgent at 1.15V, and VCCIO at 1.15V - no post.
I've even tried giving generous latency as a failsafe, up to CL18 with adjusted other primary timings mimicing Corsair XMP profiles from other kits.
I've also tried loosening the tertiary _DR -timings (the few I could find in BIOS) which should go easier on the IMC, but without luck.

My relevant system specs:
- Motherboard/Chipset/BIOS: Asus X99-A, American Megatrends, version 3402 (not using the latest one 3505 as it screwed everything up and I had to revert back)
- CPU: i7 5820k (Haswell-E)
- RAM: 2x 8GB (=16GB) Corsair Vengeance 2400MHz 14-16-16-31, dual rank, dual channel/1DPC

You're in the wrong forum for a question like that. Try OCN. You'll get better answers from a group of people that have a lot of knowledge.

http://www.overclock.net/f/

 

[steffeeh]

Posted there as well

 

[Vellinious]

Ya know...memory kits are binned pretty harshly. There's usually SOME room for overclocking, but you won't always get what you're looking for. I had a 5820k before the 6950X and was running the TridentZ 3200 14 14 14 34 sticks with it at the rated speed just fine. Ran them at 3400 same timings for benchmarking. You might just be at that point with that memory, that you'll just have to add a ton of volts to get it to run higher.

If you're looking for a daily clock, I probably wouldn't want to go above 1.4v, but I'd try as high as 1.45 (with active air flow) just to see where that next level is at. Could also try to bump the system agent voltage up a tad more. I always ended up using a .125v offset....might help.