Wandering Thoughts archives


The annoying question of Intel CPU support for XMP RAM profiles

I said something on the Fediverse:

Once again I must applaud Intel for making it as hard as possible to find out if XMP RAM profiles work on Intel desktop CPUs that can't be overlocked (non-K series, or whatever it is today). Will they give you a definite answer, even in their website's XMP FAQ? Of course not.

(And I genuinely don't know what the answer is, especially today.)

Here, 'XMP' is the common and official abbreviation for '(Intel) Extreme Memory Profile, which potentially allows you to run your DIMMs at higher speeds than the official JEDEC RAM timings. AMD has an equivalent version (cf Wikipedia), but apparently many AMD motherboards also support using XMP DIMM timing information. As covered in the WikiChip entry on XMP, XMP information comes from the DIMM(s) via SPD and as far as I know is then interpreted by the BIOS, if enabled.

The situation with XMP/EXPO support on AMD desktop Ryzen CPUs is straightforward; as far as I know, they all support it, leaving you only a question of whether the motherboard does. The situation with Intel CPUs is much less clear, and this is a deliberate choice on Intel's part. Having poked around, there seem to be two answers.

The practical answer is that it seems that non-overclockable Intel desktop CPUs have traditionally supported XMP; I've even seen assertions in online sources that faster XMP speeds mostly don't involve the CPU at all, so it's all up to the motherboard and its BIOS. It used to be that you had to use Intel's top end Z series chipsets to get XMP support, but these days apparently B series chipsets also support it. So it seems likely that if you buy a non K-series Core series desktop CPU and pair it with XMP capable DIMMs on a suitable motherboard, you will get faster RAM.

(How much of a difference faster RAM will make is an open question, but I've read some things that suggest it's especially helpful if you're using integrated graphics, as I am on my problematic home desktop.)

The Intel answer is that while Intel won't say that you have to have an overclockable K-series Core desktop CPU in order to use XMP, all of their examples of qualified DIMMs and systems with desktop CPUs use overclockable ones as far as I can see. Intel certainly wants you to buy a K-series Core i5/i7/i9 CPU if you want to use XMP and it will clearly do quite a lot to nudge you that way without actually saying anything untrue that could get it in trouble with authorities (such as 'on desktop CPUs, you must have a K-series overclockable CPU', which is likely false today since Intel isn't actually saying that).

Since Intel only officially qualifies K-series Core desktop CPUs, this lets Intel off the hook if XMP doesn't work with a non-K CPU in your configuration, even if it looks like everything should be fine. Will the uncertainty help push you toward spending a bit extra on a K-series CPU? Intel certainly hopes so. With that said, it does appear that the price difference between K-series and non K-series CPUs may have gotten fairly small (for the moment). Still, the whole thing is yet another irritation of dealing with Intel's desktop CPU market segmentation.

(I wrestled with DDR RAM speed questions a few years ago, with no answers then either.)

tech/IntelCPUsAndXMPAnnoyance written at 21:39:29; Add Comment

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