5 ms·

> Wow is it slow to POST My understanding is that it is intentionally slow the first time you boot but should be normally slow after that. Apparently it is try

> Wow is it slow to POST My understanding is that it is intentionally slow the first time you boot but should be normally slow after that. Apparently it is trying how fast it can clock the memory or something like that.

zamadatix 4y ago
It is _ridiculously_ slow on first boot after a cleared CMOS due to the extra memory training - as in minutes. 20 seconds to post is the normal time after that initial boot and a decent time at that for these boards.
- josephg 4y ago
  Any idea why they're so slow to post? Or if this is something that can ever be fixed? The b550 (zen 3) board I replaced was way faster. I wouldn't mind so much if suspend & resume worked.
  - zamadatix 4y ago
    Suspend + resume works for me on Windows, haven’t tried Linux yet so can’t say if it’s in that half or maybe something board/firmware revision specific though. Not sure why they take so much longer. Zen 3 was definitely faster for me as well. I’m not holding my breath that it’ll get significantly faster but I suppose it’s possible an update could do it.
    - josephg 4y ago
      > haven’t tried Linux yet so can’t say if it’s in that half or maybe something board/firmware revision specific though. Its probably just bugs in the 5.15 kernel I'm still running. Full zen 4 support wasn't added until linux 6.0, so I think I'm doing well as it is. Fingers crossed suspend is fixed by a newer kernel. Given everything else in the system seems to work fine, I'm not too fussed.
  - seritools 4y ago
    First-gen products often have issues like this. My old X370 board (zen1 era) turns off and on again twice before actually booting; a similar zen3 system doesn't need that and boots faster in general.
zaarn 4y ago
it's doing DDR Training. It's not necessarily how fast it can clock the memory. It's essentially putting an oscilloscope to the memory traces and checking how to generate the necessary signals fast enough while still being recognized on the other end. Simply because at the clock speeds and latency requirements of DDR5 Memory, the signal path is unique enough between CPUs, Motherboards and RAM Sticks that you need to configure the clock generation individually for that setup.
- josephg 4y ago
  That makes sense for first boot. But does it really have to do some variant of that every time the system boots up?
  - jalbertoni 4y ago
    How would it know if you haven't changed your RAM? Consider that using the same settings with different parts might lead to subtle instability, not a full on-boot crash.
    - mnd999 4y ago
      Surely it can know that. Don’t ram chips identify with vendor / serial number etc?
      - sgtnoodle 4y ago
        Serial numbers that are supposed to be unique aren't necessarily unique. I would guess that the BIOS talk to an EEPROM on the RAM modules rather than to the memory chips themselves. It would be very easy for a manufacturer to flash identical contents to every EEPROM in a batch, or with a sequentially increasing serial, rather than bother with a database.
      - zaarn 4y ago
        What if you reinsert the same RAM stick into the same slot? Minute differences in insertion force and direction can lead to the frequency response of the RAM stick changing. Data paths might now be a micrometer long and require the BIOS to retrain the communication controller to compensate for that. DDR5 tops out somewhere around 8 Gigahertz clock speed, which means the data signals travel 3 centimeters before the next clock signal arrives. At those time scales it means you're going to have to align those data signals down to the micrometer if you want them to be properly received.

zamadatix 4y ago

It is _ridiculously_ slow on first boot after a cleared CMOS due to the extra memory training - as in minutes. 20 seconds to post is the normal time after that initial boot and a decent time at that for these boards.

josephg 4y ago
Any idea why they're so slow to post? Or if this is something that can ever be fixed? The b550 (zen 3) board I replaced was way faster. I wouldn't mind so much if suspend & resume worked.
- zamadatix 4y ago
  Suspend + resume works for me on Windows, haven’t tried Linux yet so can’t say if it’s in that half or maybe something board/firmware revision specific though. Not sure why they take so much longer. Zen 3 was definitely faster for me as well. I’m not holding my breath that it’ll get significantly faster but I suppose it’s possible an update could do it.
  - josephg 4y ago
    > haven’t tried Linux yet so can’t say if it’s in that half or maybe something board/firmware revision specific though. Its probably just bugs in the 5.15 kernel I'm still running. Full zen 4 support wasn't added until linux 6.0, so I think I'm doing well as it is. Fingers crossed suspend is fixed by a newer kernel. Given everything else in the system seems to work fine, I'm not too fussed.
- seritools 4y ago
  First-gen products often have issues like this. My old X370 board (zen1 era) turns off and on again twice before actually booting; a similar zen3 system doesn't need that and boots faster in general.

zaarn 4y ago

it's doing DDR Training. It's not necessarily how fast it can clock the memory. It's essentially putting an oscilloscope to the memory traces and checking how to generate the necessary signals fast enough while still being recognized on the other end. Simply because at the clock speeds and latency requirements of DDR5 Memory, the signal path is unique enough between CPUs, Motherboards and RAM Sticks that you need to configure the clock generation individually for that setup.

josephg 4y ago
That makes sense for first boot. But does it really have to do some variant of that every time the system boots up?
- jalbertoni 4y ago
  How would it know if you haven't changed your RAM? Consider that using the same settings with different parts might lead to subtle instability, not a full on-boot crash.
  - mnd999 4y ago
    Surely it can know that. Don’t ram chips identify with vendor / serial number etc?
    - sgtnoodle 4y ago
      Serial numbers that are supposed to be unique aren't necessarily unique. I would guess that the BIOS talk to an EEPROM on the RAM modules rather than to the memory chips themselves. It would be very easy for a manufacturer to flash identical contents to every EEPROM in a batch, or with a sequentially increasing serial, rather than bother with a database.
    - zaarn 4y ago
      What if you reinsert the same RAM stick into the same slot? Minute differences in insertion force and direction can lead to the frequency response of the RAM stick changing. Data paths might now be a micrometer long and require the BIOS to retrain the communication controller to compensate for that. DDR5 tops out somewhere around 8 Gigahertz clock speed, which means the data signals travel 3 centimeters before the next clock signal arrives. At those time scales it means you're going to have to align those data signals down to the micrometer if you want them to be properly received.