XMP for non-K CPU???

[tonymc]

For some time now I have the following doubt:

I understand that applying XMP (RAM on a motherboard) when it exceeds the default memory frequency of the CPU is overclock and therefore should only work on K CPU with motherboard that allows overclock

(For example, the maximum RAM memory by default of the Core i7 7700K is 2400MHz, however on a Z270 motherboard, you can activate XMP and set the RAM to 3200MHz)

However there are motherboards that allow you to do the same with non-K CPU, for example having the core i7 7700 on a Z270 motherboard, you can activate XMP and put the RAM at 3200MHz in the same way as the i7 7700K)

There are motherboards that do not allow this.

For example on an Asrock z97 Extreme 4 with a core CPU i7 4770 can activate XMP RAM at 2400MHz, when the maximum frequency supported by this CPU is 1600MHz and the CPU is non-K, however on the motherboard Gigabyte Z97-HD3 this can not be done.

I have also seen problems to activate 3000 MHz RAM memory with a Core i7 6700 CPU on the Asrock Z170 Fatality k4 motherboard

My question is this, why does this work on some motherboards and not on others? What is the difference?

I would greatly appreciate if someone attached in the response some scheme on this subject.

Thank you very much in advance.

[Windows7ge]

The way your CPU speed is determined is by the system FSB (Front Side Bus) also known as Base Clock multiplied by the CPU's multiplier. If the motherboard only allows the RAM to be set to, lets say 2400MHz but the RAM is 2666MHz then enabling XMP the system will increase the FSB and may decrease the multiplier in order to get the memory to 2666MHz while keeping the CPU ~ the same. With a non-K chip it can only tweak the FSB which controls the communication between the CPU/RAM/North Bridge/PCH (I believe anyways) and many other components. If the CPU multiplier can't be tweaked and the FSB has to compensate for all of it then it's up to how the motherboard was designed to tweak it's own settings in order to get the RAM up to clock and keep the system stable because consequently the CPU will be overclocked too along with every other component. This can destabilize everything.

[Jurrunio]

31 minutes ago, tonymc said:

My question is this, why does this work on some motherboards and not on others? What is the difference?

Blame the manufacturer's BIOS. It should be doable as long as the chipset supports overclocking.

 

16 minutes ago, Windows7ge said:

With a non-K chip it can only tweak the FSB

no, on LGA 1155 and 1150 the BCLK (FSB name changed since LGA 1155 to BCLK) is strapped with the PCIe bus and going past 110MHz is impossible without crashing or stupid-high voltages. In other words if your statement is true, then no one on locked Haswell CPUs will be getting past 1866 memory frequency (116.6MHz BCLK, good luck stabilizing that)

[tonymc]

3 hours ago, Windows7ge said:

The way your CPU speed is determined is by the system FSB (Front Side Bus) also known as Base Clock multiplied by the CPU's multiplier. If the motherboard only allows the RAM to be set to, lets say 2400MHz but the RAM is 2666MHz then enabling XMP the system will increase the FSB and may decrease the multiplier in order to get the memory to 2666MHz while keeping the CPU ~ the same. With a non-K chip it can only tweak the FSB which controls the communication between the CPU/RAM/North Bridge/PCH (I believe anyways) and many other components. If the CPU multiplier can't be tweaked and the FSB has to compensate for all of it then it's up to how the motherboard was designed to tweak it's own settings in order to get the RAM up to clock and keep the system stable because consequently the CPU will be overclocked too along with every other component. This can destabilize everything.

I understand that FSB no longer exists from LGA 775, but I know what you are referring to, but this is not the case, the base frequencies of the CPU are intact at 100Mhz, which is what the CPUs are currently using (I do not know where Extreme range).

[Windows7ge]

1 minute ago, Jurrunio said:

no, on LGA 1155 and 1150 the BCLK (FSB name changed since LGA 1155 to BCLK) is strapped with the PCIe bus and going past 110MHz is impossible without crashing or stupid-high voltages. In other words if your statement is true, then no one on locked Haswell CPUs will be getting past 1866 memory frequency (116.6MHz BCLK, good luck stabilizing that)

Damn manufacturers changing names all the time making things hard to memorize unless you pay attention to everything coming out as it comes out.

 

I might as well ask, what do you think someone's luck would be BCLK overclocking a Xeon on the X79 chipset?

[tonymc]

4 hours ago, Jurrunio said:

Blame the manufacturer's BIOS. It should be doable as long as the chipset supports overclocking.

 

z97 and z170 support overclocking with CPU K, in this there is no doubt and it works, but there are motherboards that allow you to overclock RAM to a non-K CPU, as they do?, is my question considering that it is assumed that RAM memories are directly connected to the CPU RAM controller, or there are motherboards that incorporate intermediate electronic circuits and that's why this works.

[Windows7ge]

7 minutes ago, tonymc said:

I understand that FSB no longer exists from LGA 775, but I know what you are referring to, but this is not the case, the base frequencies of the CPU are intact at 100Mhz, which is what the CPUs are currently using (I do not know where Extreme range).

All I can say is that's my interpretation of what's going on with what you're asking. I openly accept being incorrect about something so long as I learn the correct answer in the process.

[Jurrunio]

1 minute ago, tonymc said:

z97 and z170 support overclocking with CPU K, in this there is no doubt and it works, but there are motherboards that allow you to overclock RAM to a non-K CPU, as they do?, is my question considering that it is assumed that RAM memories are directly connected to the CPU RAM controller, or there are motherboards that incorporate intermediate electronic circuits and that's why this works.

I'm saying that memory overclocking should be possible on all boards that support overclocking. Why some boards don't work I don't know, I'll blame the manufacturer for being lazy.

 

5 minutes ago, Windows7ge said:

I might as well ask, what do you think someone's luck would be BCLK overclocking a Xeon on the X79 chipset?

not great, unless it's one of those unlocked Xeons

 

[tonymc]

3 hours ago, Windows7ge said:

All I can say is that's my interpretation of what's going on with what you're asking. I openly accept being incorrect about something so long as I learn the correct answer in the process.

ok, it's the right attitude, the important thing about the debate is that we all learn.

[Windows7ge]

2 minutes ago, Jurrunio said:

not great, unless it's one of those unlocked Xeons

EXCELLENT, that's exactly what I wanted to hear...and no it's not.

[tonymc]

7 hours ago, tonymc said:

RAM memories are directly connected to the CPU RAM controller,

more information on this topic.

https://communities.intel.com/thread/61082

[tonymc]

On 10/30/2018 at 12:18 PM, tonymc said:

For some time now I have the following doubt:

I understand that applying XMP (RAM on a motherboard) when it exceeds the default memory frequency of the CPU is overclock and therefore should only work on K CPU with motherboard that allows overclock.

For example on an Asrock z97 Extreme 4 with a core CPU i7 4770 can activate XMP RAM at 2400MHz, when the maximum frequency supported by this CPU is 1600MHz and the CPU is non-K, however on the motherboard Gigabyte Z97-HD3 this can not be done.

This weekend, I will draw important conclusions on the subject, I already have a small laboratory. I will share experiences here.