How intel or AMD lock they're CPU multiplier

[skycat2216]

Just like title

I'm wondering about how to lock multiplier in CPU manufacturing.

It's hardware lock?or just using intel® ME or AMD® PSP to control UEFI Ratio options?

 

BTW,does anyone know about intel Xeon V2 Family datasheet volume 1 and next?

xeon-e5-v2-datasheet-vol-2.pdf

[alatron978]

It has to be a hardware lock otherwise someone would have modded a CPU to unlock the multiplier.

[skycat2216]

can we use EFI file to set up multiplier?

Also Why E5 v3 can overclock to tubro ratio max?

[GoldenLag]

Can be Hardware, but in the case of Ryzen it is seemingly just a BIOS thing. Athlon 200GE got unlocked by accident. 

 

Though it can be either.

[.Apex.]

It's definitely hardware lock, and i hope Intel wakes up someday and unlocks all their CPU's like AMD, Intel can actually be really competitive if they didn't lock their CPU's.

[skycat2216]

I start to thinking about those EFI file,can these little cute file(wait what?) open the lock?(like set all ratio to 40X or something)

[Jurrunio]

Software. the microcode to be specific, without Intel's in-house program modding that is absolute hell.

 

18 minutes ago, alatron978 said:

It has to be a hardware lock otherwise someone would have modded a CPU to unlock the multiplier.

12 minutes ago, _Syn_ said:

It's definitely hardware lock, and i hope Intel wakes up someday and unlocks all their CPU's like AMD, Intel can actually be really competitive if they didn't lock their CPU's.

I would love to know how you could lock a value in some code with hardware. It's not like they made the multiplier write-protected, otherwise underclocking won't work either.

 

19 minutes ago, skycat2216 said:

can we use EFI file to set up multiplier?

Also Why E5 v3 can overclock to tubro ratio max?

EFI is just the boot process file, tells the CPU what to do in the boot process. Your clock multipliers are already set at this point so you cannot.

 

E5 v3's single-core-turbo on all cores is a bug done by NOT executing part of the microcode. I only know this far because that's what I was told to do when unlocking the CPU and after the mod the CPU was not recognized by CPU-Z.

 

don't PM me for instructions

[.Apex.]

5 minutes ago, Jurrunio said:

Software. the microcode to be specific

Microcode is on a hardware level, otherwise all programmable chips would be called software

[Jurrunio]

1 minute ago, _Syn_ said:

Microcode is on a hardware level, otherwise all programmable chips would be called software

a programmable chip is a hardware that contains software inside, what's the matter?

[skycat2216]

I'm pretty sure EFI file can be use on setting ratio,at least is work on E5 v3 Dual way socket Motherboard

[X_X]

13 hours ago, Jurrunio said:

E5 v3's single-core-turbo on all cores is a bug done by NOT executing part of the microcode. I only know this far because that's what I was told to do when unlocking the CPU and after the mod the CPU was not recognized by CPU-Z.

The E5 v3 all turbo works the same way as desktop/mobile Haswell. IOW finding a early microcode patch that doesn't fix the all core errata or not using any patch until the full core turbo is properly set. Never heard of the CPU not being recognized from such deeds, perhaps you have done something extra special to achieve that.

 

@skycat2216 The original v3 EFI file was for people who were kind of lost without BIOS buttons to push, really more of a proof of concept. People were supposed to modify their BIOS instead but seems nobody really took that path

[skycat2216]

That mean we can use modify UEFI BIOS to overclock?

[Jurrunio]

3 hours ago, skycat2216 said:

That mean we can use modify UEFI BIOS to overclock?

in theory yes... in practice that's exceedingly rare

[X_X]

On 3/23/2019 at 11:32 AM, skycat2216 said:

That mean we can use modify UEFI BIOS to overclock?

It means it's typically better to do the modifications before POST.

 

For instance with the E5 v3 all core turbo the Asrock X99 Taichi hides some items such as the FIVR menu so we can unhide those. We can also add our own code, I have added a new menu "V3 - All Turbo" in my own BIOS

 

This sub-section offers a choice of microcodes since people were claiming one microcode worked better than another. Microcodes are made available for CPUID's 306f2, 306f1 and 306f0. Some people were experiencing failure to POST with 306f1 when the microcode was removed so this modification would make the necessary changes for all core turbo AND apply the microcode afterward but before the troublesome module that the BIOS would usually halt on. Unfortunately after showing people how to run all cores on the Anandtech forum, in particular "The Stilt" prices of second hand v3 Xeon's became too much for my budget so never got to do any real testing except for my original 14 core E5-2683 v3. Might have shot myself in the foot with that one.

 

Microcodes

[skycat2216]

what about Xeon E5 v2 ?

is it same?

[X_X]

Sorry @skycat2216 I have no experience with v2 and can only comment on my findings with v3. Haswell is perhaps a special case.

[skycat2216]

Wait... I have a E5 v2 datasheet,can I find something about multiplier in it?

[X_X]

In that one you can check that P_State_Limits isn't limiting your ratio but a lot of the settings you want are int the SDM mostly under the MSR section such as MSR 0x198, 0x199, 0x1A0. Limits may or may not exist in both MSR and MMIO so you would need to check especially as some might not be documented.