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SOLVED Common question :) Will Crucial work with Crucial

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jbooker

New Member
Joined
Oct 20, 2019
I have Crucial 8GB (2 x 4GB) DDR4 2133 Model CT2K4G4DFS8213 (Link), and have been running them fine for 3 years. I am on a ASRock Z170 Pro4S LGA 1151 Intel Z170 MB, But I needed more RAM a year ago. So, I finally just purchased Crucial 16GB (8GBx2) DDR4 2400 Model CT2K8G4DFS824A (Link), not expecting to keep my 2x4gb sticks but went with this type in hopes maybe I can squeeze 24GB in there. No need to throw away a perfectly good set and that same set I have is unavailable on Newegg and $117 on Amazon (Link), I'm certain I got this set for $40 when I built this 3 years ago.. So I went with the new model at 16GB just in case they don't work with my current sticks. ;-) 24 would be nice tho

A couple question while I wait for my amazon ship, if you don't mind. :)
Both are Single rack x8 and close enough in brand/model that they should work together giving me a total of 24GB, yes? Will the 2400 scale down to match the set at 2133 if they do?
I seent a post on here about overclocking the Model CT2K4G4DFS8213 but I have never overclocked, would it be fairly safe for me to overclock the 2133 set to 2400 on my motherboard? Should I just not bother and keep them running at 2133?
What you think? :D

I also have a Skylake i3-6100 right now plan on upgrading to i5-6600k or i7 around next month.
 
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Zerileous

Senior Member
Joined
Jun 21, 2002
Well it can't hurt to try, if you need the capacity. Running dissimilar ram can cause decreased performance and instability, but there's also a good chance it will be okay. If you find yourself approaching 16GB of memory usage in practical applications, then give it a try. To start out I would just stick with the new kit and see how that goes.

Both are Single rack x8 and close enough in brand/model that they should work together giving me a total of 24GB, yes?
Actually it is the brand and series of the memory chips that matters, not the sticks. With Crucial we know they will be using Micron chips (since Crucial is a Micron brand), however the product photos don't include these details, as they probably use multiple ICs even within the product SKU, depending on availability.

Will the 2400 scale down to match the set at 2133 if they do?
All DDR4 will default to 2133MHz, even if you remove the old sticks. In order to run at 2400MHz you'll need to enable the XMP profile in the BIOS.

I seent a post on here about overclocking the Model CT2K4G4DFS8213 but I have never overclocked, would it be fairly safe for me to overclock the 2133 set to 2400 on my motherboard? Should I just not bother and keep them running at 2133?
Again you can always try it, but I would wait until you actually need more than 16GB first. In a lot of ways, enabling the XMP profile in the BIOS is a sort of overclock, in that it exceeds base spec. The difference is that it has been tested at that speed and the settings stored on the memory stick. I'm not sure if the BIOS will let you enable the XMP profile of the new sticks with the old ones still installed. Otherwise you would have to enter the settings manually. It's not a huge overclock so I wouldn't be surprised either way if it worked or did not work. Having dissimilar sticks certainly won't help. Overclocking always involves risk, I don't believe that the word "safe" should be applied to an overclock. That said, I would be very surprised if setting the old kit to the settings stored in the XMP profile of the new kit caused it any kind of damage. It is of course possible that an incorrect setting (namely voltage) could damage the sticks.

It is also possible that any combination of the kits, with or without an overclock, would cause the system to exhibit instability leading to data loss (primarily of data stored in the DRAM). Some users might not consider such a condition to be "safe" although physical damage to the hardware has not occurred.

To further clarify, all of the memory in the system will run at the same speed, regardless of what the memory is rated for. You have to enter the BIOS when the system boots up and manually enable a setting called XMP to get the new sticks to run at 2400. I am unsure of whether or not your motherboard will give you the option if you have both sets installed. You can also enter the same settings that enabling XMP changes but it requires changing more settings and timings.
 

Woomack

Benching Team Leader
Joined
Jan 2, 2005
In general when you buy Crucial RAM with the same product number then it will for sure work. If you pick a different capacity or speed then it's not always compatible regardless of brand. You can try to use lower capacity memory modules in first slots so for Intel 100+ chipset series it's slot 2/4 counting from the CPU side.
 
OP
J

jbooker

New Member
Joined
Oct 20, 2019
Thanks for the replies! The sticks are in route to be here tomorrow. I like a lot of chrome tabs open sometimes, and with that plus a couple of other little programs I'm almost at 5GB used ram out of my 8. This is my game rig so even when I close chrome there's not much left for ram hungry games. Rust (the game) will crash the moment I open chrome with no tabs, and use 110% ram the entire time I manage to keep it running. 16 may be enough, but tis nice to have more. :)
For gaming how big of a deal is that little extra speed? Would I notice 2133vs2400 in the game world?
 

Zerileous

Senior Member
Joined
Jun 21, 2002
Yes probably, at least in CPU bound titles. What resolution are you playing and what GPU? Although were certainly not talking more than 10fps average. The other factor is running in dual channel, and you may lose a few FPS if your not in dual channel. Running both kits may force the board out of dual channel, it may not, idk. You can always try it.

I really don't think any games will need more than 16GB. If you really need to leave your tabs open it might make a difference, but I bet you can have your tabs and games open and still remain under 14GB used.

This video may give you more information about that question, I didn't watch it though:
 

mackerel

Member
Joined
Mar 7, 2008
All DDR4 will default to 2133MHz, even if you remove the old sticks. In order to run at 2400MHz you'll need to enable the XMP profile in the BIOS

Not the whole story. JEDEC speeds are defined lower and higher than 2133. It just turns out for some reason most enthusiast ram only has a SPD profile defined for 2133. I think I've seen a module or two with SPD profiles at 2400, so it will run at that without going into bios settings. Generally a system runs at the highest SPD speed defined in the module up to the CPU supported speed. A work Dell box for example has 2666 SPD ram in it. No overclocking options, no XMP in bios. When I put in my 3200 ram to try it out, it would only run at 2133.
 
OP
J

jbooker

New Member
Joined
Oct 20, 2019
Yes probably, at least in CPU bound titles. What resolution are you playing and what GPU? Although were certainly not talking more than 10fps average. The other factor is running in dual channel, and you may lose a few FPS if your not in dual channel. Running both kits may force the board out of dual channel, it may not, idk. You can always try it.

I really don't think any games will need more than 16GB. If you really need to leave your tabs open it might make a difference, but I bet you can have your tabs and games open and still remain under 14GB used.

This video may give you more information about that question, I didn't watch it though:

I game on a Radeon RX480 [email protected] and I've been pretty happy with the performance of most games I want to play, for the money I've put in it. Once I get a better CPU I think I'll be happy another 2 years with it again.
I don't care so much about adding to my average FPS rather then having a more stable fps, would the speed of ram help that?
Maybe I will just use the 16 kit if I have to mess around too much but I just hate not knowing what to do with my 8 kit. The idea of it sitting in my closet will haunt me.

I kinda can't wait to pop them in after work and see what happens lol.

Edit: Out of work, installation complete. -

Everything worked as I expected/hoped. :) I first took out my 8gb kit and ran bios with the 16gb kit alone to make sure they were not DOA. Everything checked out in Bios, dual channel @ 2400 speeds no XMP needed. Shuter down and jammed my 8gb kit back in, boot bios first. Bios showed I was still dual channel and all 24gb, 2133. Cool, so boot windows and I checked out CPU-Z and everything looks good in there. Now before I think about overclocking my 8gb kit should I run any tests? There was mention of possible instability leading to data loss, are there other ways I can know that wont happen then just looking at bios and cpu-z?
 
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Woomack

Benching Team Leader
Joined
Jan 2, 2005
Not the whole story. JEDEC speeds are defined lower and higher than 2133. It just turns out for some reason most enthusiast ram only has a SPD profile defined for 2133. I think I've seen a module or two with SPD profiles at 2400, so it will run at that without going into bios settings. Generally a system runs at the highest SPD speed defined in the module up to the CPU supported speed. A work Dell box for example has 2666 SPD ram in it. No overclocking options, no XMP in bios. When I put in my 3200 ram to try it out, it would only run at 2133.

A bit off topic ...
Older IC are designed for 2133, most new are 2400-2666. There are no higher rated IC just because it would made memory manufacturers to release memory kits at much more relaxed timings. Even though memory can work at tighter timings then higher SPD kits are simply always slower or are used in higher frequency memory kits at more relaxed timings.

In gaming/enthusiast memory kits is almost only like that:
- Samsung 2133 older and 2400 newer IC, Samsung B is officially discontinued but new memory kits are using or available stock of 2133 IC or last batches of 2400, for example HyperX 4000+ are all on 2400 SPD, everything from GSkill is on 2133 SPD.
- Hynix 2133 older and 2400/2666 newer IC
- Micron 2133 older and 2400/2666 newer IC
- Nanya 2133 and 2400, I have no idea which one is new and which one is old as barely anyone was using them in higher series memory kits
- SpecTek 2133/2400 older, 2666 newer, similar situation, can be mixed ... there are new 4000 Corsair kits based on this IC

2933 and 3200 JEDEC specs is out for longer just as I mentioned, not ready for enthusiast/gamers products.
Also, manufacturers (or even users) can program SPD to run at higher clock without XMP profile. Memory clock can be adjusted down if chipset/motherboard doesn't support so high clock. For example when you use 2933 SPD on Intel B360 motherboards then it will run at 2666.

Series like HyperX FURY can have programmed SPD=XMP so will run at declared speed regardless of settings in BIOS.
Notebook gaming memory can also have higher speed in SPD than for what was IC designed. For example I have Samsung B SODIMM which is rated at 3800 but SPD has at 2666 and IC was designed for 2133.

Edit: Out of work, installation complete. -

Everything worked as I expected/hoped. :) I first took out my 8gb kit and ran bios with the 16gb kit alone to make sure they were not DOA. Everything checked out in Bios, dual channel @ 2400 speeds no XMP needed. Shuter down and jammed my 8gb kit back in, boot bios first. Bios showed I was still dual channel and all 24gb, 2133. Cool, so boot windows and I checked out CPU-Z and everything looks good in there. Now before I think about overclocking my 8gb kit should I run any tests? There was mention of possible instability leading to data loss, are there other ways I can know that wont happen then just looking at bios and cpu-z?

I'm glad it works for you
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