I have Intel NUC (model NUC8i7BEH) and 32Gb DDR4 2666MHz Kingston SO-DIMM memory (model HX426S15IB2K2/32 (2x16Gb KIT)): https://www.kingston.com/en/memory/search?partId=HX426S15IB2K2%2F32.
The Intel NUC supports memory with 2400MHz frequency:
System Memory for Intel® NUC Kits NUC8i7BE, NUC8i5BE, and NUC8i3BE
Is it safe to install 2666MHz memory to the Intel NUC? Will this void the warranty?
Note: there is similar question https://forums.intel.com/s/question/0D50P00004Ww4QZSAZ/nuc8i7beh-and-ddr4-3000-mhz, but the answer is not clear for me.
No, it will not invalidate your warranty. However, did you really want Kingston memory?
Your memory is not on the compatibility list. No 2666 memory is on the compatibility list:
It may work, it may not.
> However, did you really want Kingston memory?
Actually I want to install 32Gb memory using dual channel, i.e. 2x16. Kingston is just an option.
> Your memory is not on the compatibility list. No 2666 memory is on the compatibility list:
Yes, but there is no 2x16Gb compatible memory in the list. As I understand 2 independent 16Gb memory modules may not work in dual channel, even they are the same models. For this reason I want to buy 2x16Gb KIT. Another option from my local shop is Kingston 32Gb DDR4 2400MHz HX424S14IBK2/32: https://www.kingston.com/en/memory/search?partId=HX424S14IBK2%2F32, which is close (?) to supported HX424S14IB/16 model.
Anyway I already have 32Gb DDR4 2666MHz Kingston, and if I can safely use it without warranty void it's OK for me.
Attempting to use 2666 memory will not damage your system. I am using 2666 memory in my BE system (but none of that (IMHO crappy) Kingston memory). If the NUC is unable to operate the memory at the 2666 settings, it will lower the settings to the level supportable (2400 or 2133). If it cannot support the SODIMMs at these levels, it will fail POST and flash the power LED three times to indicate so. If you see this, you will need to replace the memory with something slower/better.
I am using the equivalent of this kit: G.Skill 16GB 2666MHz DDR4 SO-DIMM Laptop Memory Upgrade Kit (CL19) 1.20V PC4-21300 Ripjaws 2x8GB (I didn't actually purchase it from Amazon, but it is easier to point to their catalog).
Now, that said, I was using this kit because I already had it on the shelf already when I received the BE NUC. In fact, I actually don't rate G.Skill as being any better than Kingston, but, in this case, the price was wayyyy right. Being an expert in this field (before retiring, I spent 21 years working on motherboards and NUCs at Intel), I can handle memory issues when I must - and I am mostly testing NUCs, not doing anything mission-critical.
My recommendation is that you purchase DDR4-2400 memory, since that is the spec'ed memory speed for this NUC and, especially since you want to install 32GB or more, the larger the amount of memory you install, the more finicky it can become.
So, I tested 32Gb DDR4 2666MHz Kingston SO-DIMM memory (model HX426S15IB2K2/32 (2x16Gb KIT)) with Intel NUC8i7BEH and it works. BIOS shows the following memory properties:
Memory Speed 2400Mhz
Memory Clock 133Mhz
SODIMM 1 (Memory Chanel) 16GB
SODIMM 2 (Memory Chanel) 16GB
Memory Voltage 1.2V
As expected memory speed was decreased from to 2666 to supported 2400Mhz.
I still worry about warranty because of answer https://forums.intel.com/s/question/0D50P00004Ww4QZSAZ/nuc8i7beh-and-ddr4-3000-mhz from Intel team:
> Also, it is worth mentioning that this Intel® NUC is not intended to be overclocked (RAM or CPU) and altering clock frequency or voltage may damage or reduce the useful life of the processor, and other system components, and may reduce system stability and performance. Product warranties may not apply if the Intel® NUC is operated beyond its specifications.
That is more of a CYA than anything else. The maximum frequency spec'ed for a processor is the maximum frequency that they officially validate. Because nothing above that frequency is officially validated, they will always say that it might not work and they will always say that it is technically a form of overclocking and that it could damage and/or shorten the life of the processor. In reality, however, running the memory controllers at higher frequencies - presuming properly sped'ed XMP profiles are used - simply do not cause the kinds of power or thermal issues that could damage or reduce the lifetime of the processor. Now, I must qualify that answer. The further that the frequencies are above the spec'ed maximum frequency, the higher the probability of the solution not working (now, or at some point in the future). That is, purchasing 4266 memory is definitely not going to work (Aside: you can't actually purchase 4266 memory; they've never been able to get it to work at all). In your particular case, you are going only one step (one bin we call it) above the maximum supported frequency (2400 vs. 2666), so this qualification doesn't really apply.
In some previous generation NUCs, the BIOS actually forced the memory to be used at the specified maximum frequency. That is, if you installed 2666 memory, it would always be run at 2400, regardless of whether it could actually work at 2666 or not. Now, I am not sure why they did this. I mention it now because you said that you inserted the memory and it ended up running at 2400. Perhaps the BIOS is imposing this 2400 limit. If this is the case, then you do not need to worry about the fact that this memory is 2666 capable at all.
Hope this helps,