By: Travis Downs (, January 12, 2020 8:28 pm
Room: Moderated Discussions
I'd like to calculate the typical slew rate for the core voltage of a SKX CPU.

Here, you can find the minimum slew rate for the external voltage regulators needed for SKX, e.g., here:

SKX External VR Spec

From that, we can determine that the normal slew rate for Vccin (which I think is the relevant core voltage) is 25 mv/us / 4 = 6.25 mv/us.

However, this is the external voltage input, and if I understand correctly there may be another IVR on the package itself which further regulates that down to the final Vcc. For example, if we look at the VID table (Table 2-4), it ranges from 0.81 V to 2.72 V, which strikes me as too high to be used as Vcc (e.g,. MSR 0x198 reports Vcc as ~0.69 often when the CPU is running at low frequency and I imagine there are lower states).

So maybe there is some stepdown?

I'm interested in anything anyone knows, including:

- What IVR and FIVR really mean, e.g., how do FIVR and IVR differ? Is there still an in-package stepdown in either case?
- What the VR configuration is for SKL (desktop), SKL (mobile) and SKX.
- What the maximum slew rate for Vcc is in SKX (or any CPU)
- What MSR 0x198 (MSR_PERF_STATUS) is measuring: is it the VID (demanded voltage), or measured Vcc, or something else.

 Next Post in Thread >
TopicPosted ByDate
SKX IVRTravis Downs2020/01/12 08:28 PM
  SKX IVRRicardo B2020/01/13 02:28 AM
    SKX IVRTravis Downs2020/01/13 11:16 AM
      SKX IVRRicardo B2020/01/13 07:59 PM
        SKX IVRTravis Downs2020/01/14 05:05 PM
          SKL desktop/mobile doesn't have FIVR (NT)David Kanter2020/01/15 10:59 AM
  SKX IVRFoyle2020/01/13 02:53 AM
    SKX IVRTravis Downs2020/01/13 12:02 PM
      SKX IVRFoyle2020/01/13 04:01 PM
        SKX IVRTravis Downs2020/01/13 04:12 PM
  Intel IVR detailsDavid Kanter2020/01/14 08:36 AM
    Intel IVR detailsanonymou52020/01/14 12:23 PM
      Intel IVR detailsTravis Downs2020/01/15 04:29 PM
        Intel IVR detailsFoyle2020/01/16 07:22 AM
        Intel IVR detailsDavid Kanter2020/01/16 11:33 AM
          Intel IVR detailsTravis Downs2020/01/16 11:55 AM
            Intel IVR detailsDavid Kanter2020/01/16 03:23 PM
              Thanks David! (NT)Travis Downs2020/01/16 05:12 PM
Reply to this Topic
Body: No Text
How do you spell purple?