Win 8 x64 event viewer error - (MTRRs) across a sleep state transition (S4)

[gelat]

I keep getting an error when entering sleep that says The system firmware has changed the processor's memory type range registers (MTRRs) across a sleep state transition (S4). This can result in reduced resume performance.

I have eliminated startup crashes, so the system appears to sleep and wake properly, but what is this message?

I have fast boot off, no hiberfil.sys and hybrid sleep is NOT an option showing for me.

 

[usasma]

Check to see if there are any BIOS/UEFI updates available.
It doesn't (IMO) appear to be a problem - it's just that the resume may be slower due to it.

 

[gelat]

My BIOS is the lastest, it's an Asrock Z68 Extreme 4 Gen 3. If the event isn;t serious, shouldn't it be a warning and not an error?

 

[usasma]

That's something that you'll have to take up with the code-writers. I don't even try to take on issues with semantics :0)

I'm not familiar with the criteria for deciding what's an error and what's a warning - and for who decides what to classify it.

 

[cluberti]

Technically saving register data, going to sleep, and then coming back and finding something underneath Windows has changed something is definitely an error, especially if it means the system's performance will suffer until it's fixed. It can also lead to not being able to wake a PC from sleep, so yes, it's an error, not a warning. Note that there could possibly be software drivers installed that can cause this, but it's rare. One thing I've found in my experience with this particular issue is that it generally happens on systems with older UEFI hardware, booted in "legacy" or BIOS compatibility mode. I don't know why this is, but I've yet to see it on a true UEFI installed/booted system. It could be that the latter is still somewhat more rare (mostly only new machines with Win8 preinstalled), but it's what I've noticed.