Should I add these 2 old RAM sticks to my current Clevo?

I'm moving to Japan in less than 40 days so I'm dismantling/disposing of my old Clevo X7200.

I salvaged these 3 Corsair RAM sticks, model CSMO4GXM1A1333C9. They are 4GB each, and more details here.

Now I already have 16 GB of RAM, specifically 2x8192 SO-DIMM DDR3 RAM 1600MHz Crucial.

I believe that in my motherboard I have space for up to 4 slots of RAM. Should I add 2 of these 3 sticks, for a total of 24 GB of 2 mixed RAM types, or is it better not?

From my understanding, more is not always better, if the RAM is not all the same kind. Also I wonder if my computer stars using the less powerful RAM first once it finds it, which would not be what I would want. I'd just want it to only use the additional, older sticks if more memory is required, but otherwise I would want to just use the newer and better sticks first.

So what should I do?
Also what benchmarks could I run to check performance before and after adding the extra sticks?

Rest of the specs:
Chassis: Clevo P771ZM
Motherboard: Intel Z97 Chipset
GPU: GeForce GTX 980M 8192MB (8GB) GDDR5
CPU: i7-4790K | Quad Core | 8 Threads | 4,0 GHz
RAM: 16GB (2x8192) SO-DIMM DDR3 RAM 1600MHz Crucial
SSD: 512GB SSD Samsung m.2 XP941
SSD2: 256GB Crucial C300
OS: Windows 10 64 bit version 1703 (build 15063.483)
NVIDIA Drivers: 382.05

 

You know I just read an article about this the other day. I'm not an expert by any means, but I'm inclined to say no. Since the clock speeds are different your mobo may just run everything at 1333. Also, it looks like those two sticks are different voltages and I don't think that's compatible either. But, take all of that with a grain of salt. let me refer you here.

 

Ram will run at the slowest speed/timings of the set (so 1333mhz and then either the 1333mhz stick timings or what the 1600mhz have programmed in for 1333mhz for each number).

Even ignoring ram voltage I would not.

 

Okay I see, thanks for the reply guys. I guess I'll try to sell them then.

Just came to my mind though, is there any data possibly stored in the RAM that could somehow still be accessed by some expert user? Should I worry about that when giving the RAM away?

 

RAM is a fast temporary type of memory in which programs, applications and data are stored. Here are some examples of what's stored in RAM:

• the operating system
• applications
• the graphical user interface (GUI)

If RAM loses power, all data stored in its RAM is lost.
.

 

Yes, the ram constantly refreshes the cells so without power it decays in milliseconds.

 

Thanks for clearing that up guys. So I posted in seventeen facebook groups related to buy/sell in my current city (Hong Kong), doesn't seem like anyone is interested so far

 

Good luck moving it, it can be tricky with older large machines as they are far more niche.