New comp build - RAM being underclocked out of the box

[FuryoftheStars]

From after-the-fact research, I've found that what I'm about to describe is known, expected behavior, and it's really my fault (I guess?) for not doing more research on this first. I say "I guess" because I honestly didn't know this was a "thing" and thus didn't even know it was something I needed to research. But anyway....

I bought a bunch of stuff to build myself a new desktop. Last one was built 12 years ago and the mobo gave out a couple of years ago and I've only now really had the money to get a new one (been using an HP ZBook since... and it hasn't been too shabby, either!). Out of the many components ordered (I did a full fresh build, reusing nothing from my old), I bought the MSI MPG Z790 Carbon Wifi motherboard, Intel i7-13700KF proc, and 2x of the G.SKILL Trident Z5 RGB Series 64GB (2 x 32GB) DDR5 5600 desktop RAM (I was going a full RGB setup, here ). (Just to put this out there, too, I don't overclock. I prefer buying stuff with better base speeds from the start.) The RAM I bought was 5600 MHz (the highest you can really go before you have to start overclocking as far as I'm aware with DDR5), it was RGB (cool!), and had a CAS latency of 28 (which was the lowest of just about anything else at 5600 MHz that I saw (most were around 38-40)). I was kind of excited about this.

So I get everything in this past weekend, slap it all together, boot it up, and the bios shows the RAM running at 4000 MHz instead of the expected 5600 MHz. What?! Do all kinds of searching and lo and behold, that's expected! Always has been, apparently, just something about DDR5 exaggerates it more or something? Something to do with the 4 slots actually being daisy-chained (as pairs)? I don't know, I'm not going to be able to explain it well, but apparently it's all explained in this thread on MSI's boards (https://forum-en.msi.com/index.php?thre ... ng.363139/).

So, whatever, from what I've read, you can sometimes overclock the RAM back up, but not always. I go ahead and try it using XMP... highest I can get is 5200 MHz before the computer fails to boot saying the overclock failed and then reverts to previous settings.

(Edit: Failed to mention in here that I did update the bios to their latest version.)

But now I have some questions in my head about all of this:

• What happens to the CAS latency like this? I wasn't able to find much on this, just situations where the RAM got underclocked by mixing RAM, thus the "better" RAM defaults to the same as the lower RAM. Is the latency in this case now no better than any other typical 5200 MHz RAM out there? Or does it still retain some of this custom profile for the latency?
• Is there a better way? Are there better options for mobos that wouldn't have this issue (don't use the daisy-chain method)? Or would buying a 4 stick RAM kit be better vs two 2 stick kits? But then how would their speed and latency compare (and I guess this kind of depends on the answer to the above question about the underclocking affect on latency)? For example, Corsair apparently makes a 4 stick RGB kit, but it's rated as 5200 MHz (slower) and a CAS Latency of 40 (much worse). If I plug this into my mobo, will it also be underclocked and I'll just be worse off? Should I just buy a 2 stick kit of 64 GB modules? Or is the difference in all of this (even in the world of Factorio ) going to be so minor that it's not worth fretting over?

I'm asking here because in part I was looking for lower latency RAM for use with Factorio (without having to overclock) and I know fellow Factorioites would probably have some sympathy and insight here ( ), but also after reading through some of the threads in MSI's forums on this, some of the common responders to these threads were rather... erm, "high and mighty" about it all? Just didn't feel like dealing with that garbage. I do want to try to maintain that high RAM capacity, too, though, you know? The factory must grow....

[inick]

I'm not going to say much. And my input may not yield any better results. I read your post, saw nothing about updating the BIOS (or, being a new fancy board, might be better calling it the UEFI).

You're buying really recent stuff, check to see if an update is avail, and apply ONLY IF you are sure you want to, AND have a guaranteed power setup such as a UPS backup during the reflashing. Nothing like bricking brand new stuff.


I wouldn't be surprised if a flash would help, if not release the potential.

[FuryoftheStars]

Sorry, forgot to mention that.

Yes, I've updated the bios to the most recent. It came with v1.30, and this only allowed me to clock my ram up to 4800 MHz I think it was? So I tried their latest, v1.80, and this allowed me to hit 5200 MHz.

I realize now that this all has to do with my trying to use 4 dimms on this daisy-chain setup, but I'm just not sure what affect this will have on the ram timings and if maybe there are some better options. I do already have an open avenue to send this board back if I wanted to....

[Tertius]

It's difficult to judge how your RAM should work with your motherboard. The first thing I make sure if I buy RAM is to check the RAM compatibility list for my chosen motherboard on the vendor website. Should be https://de.msi.com/Motherboard/MPG-Z790 ... upport#mem for your motherboard.
You didn't give the part number (something like "F5-6000J3238G32GX2-TZ5NR") used for lookup in these lists, so you need to look yourself. A shop that doesn't list this number is a shop I don't buy from.

Sanity check:
- CPU Intel i7-13700KF - supports DDR5 up to 5600 MT/s
- motherboard MPG-Z790-CARBON-WIFI has chipset support for that CPU and is one of the chipsets designed for this CPU

So this should work with DDR5-5600 RAM with actual 5600 MHz RAM speed in general.

- you bought "G.SKILL Trident Z5 RGB Series 64GB (2 x 32GB) DDR5 5600"
- according to the motherboard manual, a kit of 2 RAM modules should be inserted into slots A2 and B2. Exactly this, nothing else.

Run CPU-Z and look what it says on the "Memory" and "SPD" tab. "Memory" is what is actually in use, and SPD is what the RAM tells about itself, including the part number to look up for in the RAM compatibility list.

Often, the bios defaults to the fastest JEDEC timing from the RAM SPD. One need to explicitly activate XMP timing.
On my system, there is a "XMP" drop down list in the EZ UEFI bios setting: I can choose between disabled and 5600 memory timing. Did you use this setting to switch your RAM from JEDEC to XMP?

If it comes to clock speeds, don't confuse RAM frequency and CPU frequency. For example, on my system (B760 chipset with a i5-13600k and DDR5-5600 RAM) I have CPU frequency of 5100 MHz and RAM frequency of 5600 MHz. Both are within specification and not manually overclocked. You shouldn't try to increase the CPU frequency to 5600 if you only want to have your ram running at its maximum speed of 5600. If I read I7-13700KF values from ark.intel.com correctly, your maximum CPU frequency should say 5300 MHz in your Bios. At least that's the value where for my slightly slower CPU 5100 MHz is listed, and 5100 is what I see in my bios.

In CPU-Z "Memory" tab you will see what is actually in use. If you maxed your RAM frequency, it should tell 2800 MHz as DRAM frequency (or slightly below). The setting on my own PC with DDR5-5600 RAM tells 2793.2 MHz, and the system was never unstable - never even one crash or hang since I built it about half a year ago. However, I bought modules with 36/36/36/76 timing.

If it comes to CAS latency and the other latency values, I found there are tradeoffs. Modules with low CAS latency have large tRAS latency. I compared cheap modules and expensive modules, assuming expensive modules are better, so the values from expensive modules are probably telling me what is faster. Then I investigated what people say about these latencies, and I found nobody definitely knows what this is about, and which values are vitally important. It's not even clear if low CAS latency is better or low tRAS latency (the last value of that 4 latency values you usually see). So I deducted these values are not that important and not crucial, so I have freedom with choosing a proper RAM module.
It was consensus that one have to run a benchmark and inspect the results, to see if some system is faster or not. But you cannot predict the performance from CAS latency values alone. It depends on the whole system. You cannot just say "CL28 is faster than CL36". It depends on the whole system. There were also voices that told the performance difference between something like CL28 and CL36 isn't really big. It can be measured, but not perceived. Nobody contradicted, so I guess there is some truth in that.

So I, for myself, chose RAM modules more on the cheaper side, not on the expensive side, with medium RAS latency. Not highest value, but also not lowest value as well. Stability is more important than performance for me, so I didn't try to push the specification all the way out.
And of course RAM whose part number is listed as compatible in the RAM compatibility list of the motherboard. The frequency as high as the maximum speed specified for CPU and chipset. This worked perfectly for me.

So what you can do for your system?
- make sure you actually changed settings for RAM frequency and not for CPU frequency
- check RAM compatibility and make sure it's listed
- make sure a kit of 2 modules is seated in A2+B2 and it's properly seated. The clips indicate proper seating.
- make sure power supply is sufficient
- make sure cooling is sufficient
- use automatic Bios configuration to clock the RAM with 5600. (it's actually 2800 MHz, but probably displayed as 5600).

As example how my RAM CPU-Z looks on my system (usually such screenshots from foreign systems are not useful, however these are from the same processor and chipset generation, so it should have some value for comparison):

1.png (81.24 KiB) Viewed 2024 times

CPU freq should be 5300 for you - you need to produce some CPU load to increase this value to max.

[FuryoftheStars]

It's difficult to judge how your RAM should work with your motherboard. The first thing I make sure if I buy RAM is to check the RAM compatibility list for my chosen motherboard on the vendor website. Should be https://de.msi.com/Motherboard/MPG-Z790 ... upport#mem for your motherboard.
You didn't give the part number (something like "F5-6000J3238G32GX2-TZ5NR") used for lookup in these lists, so you need to look yourself. A shop that doesn't list this number is a shop I don't buy from.

F5-5600J2834F32GX2-TZ5RK

It's not on their compatibility list, but reading up on the whole 4 dimms thing with the article I linked, it sounds like it wouldn't have mattered much? (Not that compatibility lists are the end all be all either, as these are typically just the things that they have had the chance or desire to physically test themselves.) I even managed to find something yesterday (that I can't by the life of me find again) showing that even Intel lists their 13th gen procs as only being rated to support up to 5600 MT/s for 1 DPC, and 4400 MT/s for 2. But I'm also not the only one to have noticed this and inquire on the MSI boards, and many of them are using RAM on the compatibility list.

(It's starting to feel like everything halfway decent is just being designed for overclockers now and the rest has to settle for stuff lower down the rung. :/)

To the rest of your post, no, I'm not confusing the two values. They have it clearly labeled. I've attached a couple of (large) images that are pictures of the bios and CPU-Z both overclocked as high as it'll let me, and not overclocked (default/auto).

Definitely have enough power. 850 Watt. And definitely not a cooling issue as I noticed these speeds on first bootup before the OS was even installed and the CPU temps have been perfectly fine. In fact, as I type this, I look at the readout on my mobo and it's showing it hanging out at 30 C.

Edit: The timings on this ram are 28-34-34-89, so no, the tRAS isn't the best, but most of the others were also in the 80s with 38 for CAS and higher numbers for the middle two. The best one I saw (iirc) for the tRAS was a 40-40-40-70 (out of the ones I was looking at). But I know that Factorio plays better with lower RAM latency, so that's what I was trying to look into. Unfortunately, all the latency calculators out there merely want MT/s and CAS. :/

[Tertius]

Looking in the RAM compatibility list (sorry to persist with this), it seems the "2834" in "F5-5600J2834F32GX2-TZ5RK" tells about the latency (probably CAS 28, rest 34, for your module). And there are only G.skill modules with 36 and 40 CAS latency listed. No 28 latency modules. May be CAS 28 latency modules from G.Skill aren't compatible with that board.

In your Bios screenshot, there are 3+2 buttons near the XMP profile button (3 normal, 2 user). What do these choose? May be different timing settings? May be you can choose some setting with a slightly higher CAS latency.

I agree that if some RAM isn't on the list doesn't mean it's not working with that board. However, you have an issue with the maximum RAM frequency, and your RAM isn't on the list, so the issue might have something to do with it. It's just a possible reason. Unfortunately, we never know if some module isn't on the list because it wasn't tested, or if it isn't on the list because of issues.

[FuryoftheStars]

In your Bios screenshot, there are 3+2 buttons near the XMP profile button (3 normal, 2 user). What do these choose? May be different timing settings? May be you can choose some setting with a slightly higher CAS latency.

#s 2, 3, and the two user ones are all disabled. I can't select them.
#1 appears to do nothing/is a blank profile.

I'm willing to try some other ram, but I think one of my primary questions still is what happens to the latency/timings of the ram in this case (of being underclocked by the board vs other ram)? Does it retain anything of the custom timings the manufacturer designed it with, or does it just default to whatever the JEDEC standards are for that MHz-MT/s that it manages to run at?

Edit: Well, actually, looking at the CPU-Z images on the Memory tab I posted, I think I can kind of see the answer to my own question, there. It seems like when I let it run at default/auto, the times do change (40-40-40-77), but when I "overclock" back up to 5200, the timings it shows are the same as what the manufacturer spec'd for 5600... so that's something, I guess. It's at least something I can work with. I mean, if whatever I replace this with, assuming it's still able to run at 5600, if the CAS value is such that it's overall latency is still worse than what I'm getting now, then I might as well stick with what I've got. (Right?) Assuming, of course, that what ever I replace it with I don't overclock.

[gGeorg]

When you build from ground up a gaming PC with Factorio in mind, I would go AMD 3D chips. This CPU line-up are way beyond Intel could offer, in gaming and especially Factorio intense computing style.
On top, with latest AGESA chipset firmware you could go RAM at 6400 synced 1:1 with CPU. it is not overclock, it is by design.

If you could send your stuff back to e-shop and replace with AMD you get much better bag for your bucks.

[FuryoftheStars]

Well, I didn't have Factorio exclusively in mind for the build, and I do have a personal bias towards Intel, but thanks for the suggestion anyway.

Over the past few days, though, I've been considering sending back this board and ram and getting something DDR4, but options seem limited, there. I was looking at both Z690 and Z790 boards that support DDR4, but there seem to be some pros and cons to each and when I narrow it down to a couple that have what I want and would work, I'm not sure I like the looks.

[gGeorg]

I do have a personal bias towards Intel,

At least you are sane enough to admit that.
You have a difficult selection now and decade into future is not shiny too.
Good luck