Why the RAM stats discrepancy?

Wayfinder

Yesterday I bought 16 gigs (2 x 8) of Corsair Vengeance LPX DDR4 RAM, rated at 3200 MHz.

I was replacing 8 gigs (2 x 4) of Ballistix 2400 MHz DDR4 RAM. Both sets were running in proper, confirmed Dual-Channel mode.

However, when I run either Speccy or CPU-Z, both show the new RAM running at 1067 MHz... whereas the old RAM clocked at 1198 MHz.

I'm wondering how 3200 MHz RAM is (apparently) running slower than years-old 2400 MHz RAM.

Anyone out there have any ideas? Thanks. : )

Wayfinder

Thanks for your quick answer Gqrbqge. I checked out a webpage regarding altering these settings on my specific motherboard, and after doing so found a significant speed increase from 1067 MHz to 1600 MHz. As indicated in the article, some motherboards are simply not designed to recognize RAM specs. That factor along with the upcoming Win 11 requirements will eventually urge replacement of my motherboard. It served me well for many years and probably will for at least a year or two more. In the meantime, I've gained some speed increase, and now have the advantage of 16 gigs of RAM. Again, thanks for your quick answer. Very helpful! : )

ChaosDTV

i notice a lot of ram defaults to a much slower speed than what its rated to do. With my corsair vengeance its rated for 3200 up to 4666 mhz and all i had to do was go in my BIOS and change the XMP from what my ram defaulted to which was 2166mhz and i boosted it to 3200 mhz and received a much needed boost in performance.

PowerSpec_MikeW

@Wayfinder @ChaosDTV

RAM is preprogrammed with profiles. They'll have standardized JEDEC profiles, ranging up to 3200 (C22) and then you may have XMP profiles programmed as well.

As an example on a G.Skill 3200 C16 kit I see 2066 C14 JEDEC profile, the 2066 C15 JEDEC and the 2133 C16 JEDEC in addition to the 3200 C16 1.35V XMP profile.. Generally when you buy memory that's sold with an XMP profile, the included JEDEC profiles are pretty basic and are there to get the system to boot. They're going to be in that low 2133 area like the kit I selected here. As the manufacturer intends for you to load the XMP. If it was JEDEC 3200 C22, you'd probably have 3200 C22, 2933, C20, 2666, 2400, 2133. The motherboard will work it's way down from the highest JEDEC profile as the board figures out what will POST successfully.

gqrbqge

Hey @Wayfinder

I'd recommend checking this article out!

https://help.corsair.com/hc/en-us/articles/360025282412-Run-DRAM-at-its-Rated-Speed-with-XMP

gqrbqge

Glad you found an answer!

Wayfinder

Thanks Chaos. That seems to have been the problem. One would think the system would just adapt to the RAM speed but it seems that has to be manually set (at least on some systems).

ChaosDTV

https://community.microcenter.com/discussion/comment/43845#Comment_43845

no problem! i dont know why it defaults to way lower than it needs to be its probably some safety type of thing just a default speed its a mystery lol

Wayfinder

I greatly appreciate the answers posted here. Two thumbs up to all of you. While I wasn't able to get the full 2400 I was hoping for, the speed did increase from 1067 to 1600. Not sure why it won't boost the rest of the way; may be a limitation of the motherboard or BIOS. Still, that's a fairly significant boost. : )

PowerSpec_MikeW

@Wayfinder

You are. You double that number that you're seeing. 1600 = 3200, 1200 = 2400, 1067 = 2133. Check task manager in windows and you'll see you're operating at 3200Mhz.

Wayfinder

*blink blink*. You are right. I checked Task Manager... and 3200 mhz.

I don't even pretend to be a deep-core tech. So could you help explain this to me. Why does 1600 = 3200? Why does a program like Speccy tell me my RAM is operating at 1600mhz, and Task Manager says it's 3200 mhz. I might need the explanation in layman's terms. ;D

Thanks for pointing that out BTW. It was kinda nice to see that 3200, even if I don't understand why (yet. Hope to soon). : )

Wayfinder

Thanks TS! That was an excellent explanation. I had actually wondered if it was something like that.

In my mind, this is kind of the computer industry "cheating" in a way. They call it 3200 memory, but if one only uses one stick they'll only get half the speed of dual channel. I'd actually had a tech hint at that when I bought the RAM but he didn't explain why. I'd asked him, "Which is better, for me to buy a single 16g stick or two 8g sticks?" He said two 8g sticks "Because they're faster if used in dual channel mode"... but he didn't go into detail and I didn't think to ask him; I just took it he knew what he was talking about (and evidently, he did).

It reminds me of the guitar industry, which rates guitar pickups by OHMs as a rating of power/volume. In reality OHMs have nothing to do with power, since ohms are a rating of electrical resistance, not electrical flow. It an industry-wide "fake" rating that almost everyone uses.

That's kind of what I see here in RAM speed ratings. They label it as 3200 memory, when in reality it's 1600 memory that "becomes" 3200 IF one uses two of them in dual-channel mode. Single channel it's only 1600.

Again, thanks for your well-explained answer. I think I somewhat understand now (or at least I have an idea of what's going on internally). Best wishes to you! : )

PowerSpec_MikeW

@Wayfinder

Well if you installed a single stick of DDR4-3200, you would still see 3200 in task manager. Double data ram. It transmits twice per clock cycle which doubles the effective clock speed. In the case of DDR4-3200 the memory sticks are individually operating at 1600Mhz, but the effective speed is 3200 MT/s. I'll correct my information from above here.

Formula or calculating bandwidth is frequency * 2 * 64 \ 8. DDR4-3200 is 1600 * 2 * 64 \ 8 = 25,600 or 25.6GB/s. This is why the model is PC4-25600. You would multiply this by the number of channels.

DDR5 would use the same formula, but we have the 2 32 bit bus instead of the single 64 bit. Bandwidth is the same, but this can greatly enhance access times with some data sets.

Wayfinder

"Formula or calculating bandwidth is frequency * 2 * 64 \ 8. DDR4-3200 is 1600 * 2 * 64 \ 8 = 25,600 or 25.6GB/s. This is why the model is PC4-25600. You would multiply this by the number of channels."

That's awesome to know. Thanks! Got more out of this question than I expected! : )

Isn't that amazing really? 25.6 GB/s. The mind boggles. It also makes me wonder how much info the human brain processes per second. I should look that up. :D

PowerSpec_MikeW

@Wayfinder

Keep in mind you're running in dual channel and you're theoretically doubling that number. Now, that's theoretical and you won't likely hit that on a benchmark, but I have hit over 60GB/s read dual channel overclocking a Patriot DDR4-4000 kit.

You also want to factor in latency as well. Generally as frequency increases so does latency. Latency is basically response time, lower is better.

CAS \ Frequency * 1000. As some examples:

3200 C16

16 / 1600 * 1000 = 10ns

3600 C18

18 / 1800 * 1000 = 10ns

3200 C22 (JEDEC)

16 / 1600 * 1000 = 13.75ns

Latency wise, this is a wash, but factoring in bandwidth the 3600 kit is a better option at 28.8GB/s, vs 25.6GB/s. Especially on AMD Ryzen platforms, as the infinity fabric runs 1:1 with the memory frequency and scales up with it.

Latency is another thing with XMP profiles, that are pushing much lower than JEDEC standards. JEDEC 3200 is C22. You're probably running C16. That's significant.

Also I'll note that JEDEC is standardized at 1.2V and most of the XMP profiles you'll see are 1.35V. The increases frequencies and lower timings are achieved at the cost of higher voltage.