3600mhz RAM default to 2666mhz. is that normal?

[thefunkygibbon]

I bought some Corsair CMK32GX4M2Z3600C18 VENGEANCE LPX 32GB (2 x 16GB) DDR4 DRAM 3600MHz C18​

a year or so ago, and its just dawned on me that they are running at 2666mhz not the 3600mhz as advertised. I've enabled XMB and now its 3600. But should i even had to have done that? Isn't the fact that its advertised as 3600mhz mean it should run at default as 3600 and the XMB should be there to run alternative timings/speeds?
(hands in the air.. its been a fair few years since i've been into this sort of thing so i've forgotten about how it all works)

 

[DoneADougalOnSofa]

No. A board will always run at default speed, unless you manually activate XMP. The RAM can't make the board do this automatically.

Soooo many people probably run their RAM way slower than it should be, simply because they don't even know about XMP- I'm talking those who aren't tremendously computer savvy, and probably buy pre-builts.

 

[thefunkygibbon]

Thanks.. i figured that the board would have recognised that it was a specific speed/timings and set to that. I'm assuming that the XMB profiles are what are built into the ram rather than what my board has defined on it?

in fairness (to me) I did enable XMB when i first got it, i guess the bios must have defaulted at some point though.

 

[DoneADougalOnSofa]

XMP is literally an overclock. It's just a pre-set profile of numbers (stored in BIOS) which ought to work, it's not guaranteed but will work 95% of the time. Any boot issues, and the board will reset to base speeds- that's a very common thing.

 

[Tetras]

But should i even had to have done that?

Seeing as you likely paid extra to purchase 3600 ram, I should think so

But, as said above, it is a (semi-automatic) overclock, so if you're not comfortable with that, then put it back.

 

[JollyJamma]

Thanks.. i figured that the board would have recognised that it was a specific speed/timings and set to that. I'm assuming that the XMB profiles are what are built into the ram rather than what my board has defined on it?

in fairness (to me) I did enable XMB when i first got it, i guess the bios must have defaulted at some point though.

XMP is an overclock. Intel used to (not sure if they still do) reject RMA claims on CPUs if the XMP profile had been enabled by the user.

It’s best to enable the profile as it improves performance. JDEC speeds (ie 2666) are very safe and slow with low speed and high timings for compatibility.

 

[mrk]

On modern Intel CPUs and boards, anything above 3200MHz is considered memory overclocking by Intel, at 3200MHz both CPU memory controller and RAM are 1:1. There's very little actual performance difference between 3200 and 3600, but there would be a difference between 2666 JEDEC and 3600 XMP. Last year I had to run my 3600 (also LPX C18) at 3200 for stability because it was only in 2023 where Gigabyte released a BIOS that actually sorted the stability out and I could enable XMP without issues. Saw little to no change in gaming fps, but it's just nice knowing that the RAM is running at what it should be.

 

[Removed User 345456]

Sorry if I sound thick? If the ram is 3600mhz then why doesn't it run at the right speed when plugged in?
Also why is it considered an overclock if you're just running it at the correct speed it's meant to? Or do you simply mean XMP is the name of the ram overclocking section on a motherboard?

 

[thefunkygibbon]

Sorry if I sound thick? If the ram is 3600mhz then why doesn't it run at the right speed when plugged in?
Also why is it considered an overclock if you're just running it at the correct speed it's meant to? Or do you simply mean XMP is the name of the ram overclocking section on a motherboard?

Yes exactly. This is what I'm confused about. I think they are implying that all memory is 2666mhz out of the factory.. but the ones sold as higher are just because they have been tested in the factory as running fine at higher clocks and therefore sold as such. I'm unsure if this is accurate description and if it is, why is this a thing for this generation of ram but it wasn't in older ddr generations?

 

[mrk]

Someone else mentioned this before but with the huge number of system variations and compatibility, the RAM has to load in a new system at JEDEC standards which is a slower MT rate and slacker timings - This ensures that the system will boot and run, so the BIOS can be entered and then the correct values dialled in or XMP enabled. This is important because not all boards support all RAM models without a BIOS update, so it's impossible for RAM makers to know what systems they will be installed in hence why we have the JEDEC standard speeds which are BIOS defaults for all modern RAM modules. If RAM was 3600MHz on first boot and your BIOS didn't support it without an update or adjustments in the BIOS, then you'd never be able to boot to do those things.

Intel's memory CPU controller runs at 3200MHz, so whilst it will work with RAM running much faster, anything above that is considered overclocking. For DDR5 Intel systems the default memory controller speed baseline is 4600MHz.

There's a good write-up of what's what for RAM vs Intel gens here: https://www.calendar-uk.co.uk/faq/what-ram-speed-does-12th-gen-intel-support

 

[Removed User 345456]

Someone else mentioned this before but with the huge number of system variations and compatibility, the RAM has to load in a new system at JEDEC standards which is a slower MT rate and slacker timings - This ensures that the system will boot and run, so the BIOS can be entered and then the correct values dialled in or XMP enabled. This is important because not all boards support all RAM models without a BIOS update, so it's impossible for RAM makers to know what systems they will be installed in hence why we have the JEDEC standard speeds which are BIOS defaults for all modern RAM modules. If RAM was 3600MHz on first boot and your BIOS didn't support it without an update or adjustments in the BIOS, then you'd never be able to boot to do those things.

Intel's memory CPU controller runs at 3200MHz, so whilst it will work with RAM running much faster, anything above that is considered overclocking. For DDR5 Intel systems the default memory controller speed baseline is 4600MHz.

There's a good write-up of what's what for RAM vs Intel gens here: https://www.calendar-uk.co.uk/faq/what-ram-speed-does-12th-gen-intel-support

I know what you're saying but usually that's 'just tough' as with putting a newer cpu in than the one required then having to arse about buying/borrowing an older cpu to flash the bios then putting your new cpu in?

It surprises me this isn't the case with ram? I mean after all you are LITERALLY buying it in YOUR chosen speed... Same as you buy a cpu for the socket the motherboard takes or a motherboard for your cpu, either or. So it's your fault if it's wrong.

 

[thefunkygibbon]

Surprised by now that motherboard manufacturers haven't just bolted on 64mb of ram or something onto the board so that it can always get into the bios for this exact reason

 

[Removed User 345456]

Surprised by now that motherboard manufacturers haven't just bolted on 64mb of ram or something onto the board so that it can always get into the bios for this exact reason

And yet you can get a flash without a cpu option on some like the msi mortar b550m where you just stick a usb stick into a dedicated rear port with a dedicated button on the rear I/O and come back in 5 mins and it's done.

Weird that some things are now more advanced yet not standardised yet ram that you choose by choice has to be messed about with to run correctly using stuff designed for overclocking.
Bit ironic and backward when you're just wanting to run it at the stock speeds it's intended for.

 

[Dg834man]

Weird that some things are now more advanced yet not standardised yet ram that you choose by choice has to be messed about with to run correctly using stuff designed for overclocking.

Its already been pointed out the ram standard is jedec, xmp/docp/expo are all ram overclocking profiles, really a hard life when you have to hit delete click on xmp then save and exit.

 

[Removed User 345456]

Its already been pointed out the ram standard is jedec, xmp/docp/expo are all ram overclocking profiles, really a hard life when you have to hit delete click on xmp then save and exit.

yeah I can read, that wasn't my point though was it.

just seems a bit archaic that the standard hasn't been updated given the current capability of motherboards being able to flash bios without a cpu etc...

 

[Orcvader]

why is this a thing for this generation of ram but it wasn't in older ddr generations?

Oh it's been around for a long time. DDR3 had it, DDR4 too and of course DDR5 as well. XMP/EXPO are just extensions to the JEDEC profiles. JEDEC speeds are generally slower/looser timings to ensure stability, but Intel knew they could run at higher speeds and/or tighter timings for performance. But these are "unofficial" as JEDEC are the ones who are in control over the standard, so that's why it must default to their speeds first.