You need to enable MCR (which trains the memory once and caches the result for (iirc) 30 days) otherwise yeah, booting is horribly slow, even the 64GB I have can take several minutes but with MCR it boots basically instantly.
replySome motherboards have it off by default.
From my comment:
reply> The 30 minute boot time could be worked around by enabling the (off-by-default) memory context restore option in BIOS
Memory training seems to be getting faster with each bios update. In 2024 when I upgraded to AM5, 64GB memory training took like 15 minutes. Now the same setup takes about a minute when it needs to retrain, then near instant with MCR (Windows 11 takes significantly longer to load than the POST process).
replyI’m in the same situation! My machine will take 2-5 minute to post every few reboots, it seems random. The messed up part is the marketing material says this things can handle 256gb of ram or whatever absurd number, f me for thinking then 128gb should be no problem. Honestly this whole thing has soured me on AMD. Yea they have bigger numbers than intel but at what cost, stability?
replyCheck you have MCR (Memory Context Restore) enabled, otherwise you train the RAM way more often than you need to (every boot).
replyYour machine takes 30 minutes to boot because of the RAM? Or it takes 30 minutes to load a model?
replyIt's the RAM. It needs to "trained" which takes some time but for for some reason these boards seem to randomly forget their training, requiring it to happen again.
replyI've never had memory training be forgotten with my AM4 nor LPDDR5-based laptops and NUCs. Is this a new thing with AM5 or something? Or just a certain brand of BIOSes?
replyhuh, its been a decade since i built a PC, whats changed?
replyDDR5 is much, much more fickle than DDR4 and earlier standards. I think it's primarily due to pushing clock speeds (6000 MT/s would be insanely fast for DDR4, but kinda slow for DDR5).
replyMemory training has always been a thing: during boot, your PC runs tests to work out what slight changes between signals and stuff it needs to adapt to the specific requirements of your particular hardware. With DDR4 and earlier, that was really fast because the timings were so relatively loose. With DDR5, it can be really slow because the timings are so tight.
That's my best understanding of it at least.
It's an AMD thing
replyMy guess is bigger numbers, higher voltages, tighter timings.
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