Corsair lpx ddr4 3000mhz cl 15 (XMP and Dual Channel Issues)

ludicitus

Prominent
Jan 13, 2018
3
0
510
Hello there,

I recently finished setting up my new rig:

Asus z370g
i5 8600k - cryorig h7 quad lumi
Corsair lpx ddr4 3000mhz cl 15
gtx 1070
OCZ zs 550w (initially, but now replaced with Corsair RM650x)

So everything is good except the configuration of my RAM which, when i enable xmp in the bios for 3000Mhz CL 15 at the stated 1.35V, appears to set the DRAM voltage to 1.36 and I have no idea why - more concerning is that the vccio and system agent voltages increase considerably too to around 1.25 and 1.28 respectively.

So far I have not tried setting the voltages or timings manually but that is an option I am willing to try but I wanted to ask here first: is there a need to overclock the cpu a little to attain a stable 3000mhz cl 15 at 1.35v and is that why my mobo is upping the voltage to keep it stable (I am running the cpu stock atm). Basically is there any connection between the cpu clock and voltages and the Ram clock and voltages? or possibly the cpu imc needing more help to run 3000mhz stable?

I assumed the i5 8600k would run this ram at the advertised speed but i am just gathering as much info as i can before i consider tweaking the cpu if that is necessary for this ram.

(update) I RMAd the first set of ram i received as windows memory test informed me there was an issue with it running at default BIOS settings (2133 mhz) - now i have put the new memory in i still get the error but my tests are confusing:

Each Ram module passes windows diagnostic and Memtest individually in any of my DIMM slots, but combined in dual channel mode they fail both test programs, with memtest reporting 1 error in 4-6 passes. So:

- Does this absolve the mobo DIMMS from consideration or is it failing to run dual channel properly?
- Could this be an issue with the CPU (imc)?
- Or, is there the possibility of mobo bios default settings not playing friendly with this RAM (in which case could someone give guidance on exactly how to set the RAM up manually as the XMP profile is problematic for the above reasons)?

I very much doubt that two brand new sets of RAM will be faulty, right?

Thank you in advance for any info you can shed on this for me.
 

ludicitus

Prominent
Jan 13, 2018
3
0
510
Okay so I have done my own tests and troubleshooting and believe I have found my own solution.

For anyone else having trouble with this motherboard and ram combination: the mobo default settings of 2133 at 1.2v cl15 are not stable. Errors in memtest were rare but they did appear every now and then, also had a few hard freezes and reboots.

Also, setting the xmp profile set the vccio, vccsa voltages way too high for comfort.

SOLUTION: for the moment I have set the ram to run at 2666 at 1.3v cl14 (cl 15 is also okay)

Now I have run windows hardware checker, memtest for a full 12 hour pass, and prime95 blend test 24 hours, prime 95 custom test using 90% ram for 24 hours and no errors whatsoever have been detected.

Basically, I can’t say for sure if it’s the ram or the mobo, but the stock bios settings are not stable.