Combining Corsair Vengeance LPX 16GB (2 x 8 GB) with 16 GB of Crucial DDR4 (4 x 4 GB)

[SidRock]

So my original build was with the Asus x99-a motherboard with 16 GB of Crucial DDR4 (4 x 4 GB). My computer kept freezing since I like to have a lot of google chrome pages + other programs open and so I bought Corsair Vengeance LPX 16GB (2 x 8 GB). I tried every combination of using the DIMM slots possible but the max RAM recognized by my machine was 24 GB. During one of these configurations, I changed my CAS latency to 10. Well, finally my mobo recognized all 32 GB but windows wouldn't boot. I tried restarting multiple times to no avail. Finally, after booting into my mobo, I pressed F8 and selected my OS drive and windows loaded without problem – all 32 GB were recognized.
The problem is that now my computer won’t boot without doing that. This happens everytime now: When I power it on, the computer turns on but the mobo doesn’t post. I have to hold down the start button and then press the start button again. On the second time, the mobo posts but it says overclocking error press F1. From here if I press F8 and select my OS it boots without problem. If I press F10 to save without making changes, the whole process repeats starting from the no post. I just updated my bios to latest and also changed the DRAM voltage as well as fooled around with the VCCIO. Nothing I change can get break this cycle and if I change the CAS back to Auto, the mobo and windows only recognizes 24 GB of RAM.
In summary please help! Thank you

 

[kanewolf]

Mixing RAM is a gamble. It sounds like you have incompatible sets and lost the bet.

 

[drivinfast247]

Just install the 2x8gb kit and call it a day.

 

[SidRock]

I was afraid that was the answer I would get. Isn't it odd though that I can get the computer to boot to windows without any issue thereafter? Is there a way, despite the incompatibility, to get the motherboard to boot straight to windows without having to manually telling it to do so after the boot fail?

 

[SidRock]

Also in terms of combining RAM, if I were to follow the provided advise and remove the 4 GB set, does the next set of 16 GB that I buy have to be Corsair LPX or can I buy from a different company provided the size and speeds are the same? I don't want to take any more chances... Thanks!

 

[USAFRet]

Also in terms of combining RAM, if I were to follow the provided advise and remove the 4 GB set, does the next set of 16 GB that I buy have to be Corsair LPX or can I buy from a different company provided the size and speeds are the same? I don't want to take any more chances... Thanks!

Unless the RAM is bought and installed as a specific matched set...it is a gamble.
Even from the same company, the same "model".

If you want 16GB, buy a 16GB set.
If you want 32GB, buy a 32GB set.

 

[SidRock]

Wait even if I buy another 16 GB set from Corsair, even the same model it may not work together with the previous set? That's nuts...

 

[USAFRet]

Wait even if I buy another 16 GB set from Corsair, even the same model it may not work together with the previous set? That's nuts...

It is more likely they would work than just 2 random RAM sticks.
But still not 100%.

Set A may have come from a factory in Thailand, Set B may come from a factory in Malaysia.
Each with slightly different tolerances.

It would *probably* work, but the only real guarantee is to buy a matched set, sold as 32GB.

 

[SidRock]

Ok crazy question coming:
What if I got a different Motherboard. Would that make it possible that the two sets are compatible ie: that it's a problem specific to the motherboard? Just asking, not a realistic solution...

 

[USAFRet]

Ok crazy question coming:
What if I got a different Motherboard. Would that make it possible that the two sets are compatible ie: that it's a problem specific to the motherboard? Just asking, not a realistic solution...

A different board is no indicator of functionality, either better or worse.

 

[SidRock]

Just as quick follow up for future users that encounter this thread:
Part of the problem with the booting came from the odd fact that my ASUS motherboard deleted my SSD with windows from the boot priority list. I found the solution to fixing this on a different thread from this website and once my SSD with windows was restored as the primary boot, most of the issues went away. The motherboard still continued to have trouble recognizing all DDR4 rams and I ended up buying the 32 gb set from Corsair. After installation using the recommended setup from asus, I was actually able to put in all my ram for a total of 48 gb. the MB again deleted my ssd boot but once I refixed it, my computer boots normally and recognizes all RAM.
Thanks everyone for their help with this!

 

[Karadjgne]

Those X99/TR4 boards mount 128Gb of ram total. I've not yet seen a 128Gb kit other than for servers. Largest kits I've seen are 4x16Gb (64Gb) so to fully fill an X99 would require 2x kits. That said, since you did have 4x4Gb already, I'd have populated the entire board with another 4x4Gb kit, matching the timings and speed, if not the vendor. Not only would (if ram is paired right according to the layout) run the ram in quad channel (offers much greater bandwidth for all those pesky chrome pages) but also offer the best possibility of compatability between 2x kits.