Refused to Post after XMP Setting in BIOS

Did some research and found to my surprise that, apparently, the XMP button can change quite a lot of things. Have never used one before. Guess I have to set the timings myself. (And why does the forum sporadically change initial letters in the middle of sentences to uppercase?)

I use an Asus H170 Pro Gaming mobo, which shows the XMP and Jedec settings of the RAM sticks, but there are no changed CPU settings displayed. I do think that no CPU settings should change, when the memory settings are changed. I would also guess that if you switch from Jedec to XMP, the voltage gets increased to 1.35 rather than 1.65. Have you updated the mobo BIOS to the latest version yet?

I have seen on my system btw, that the XMP settings of my so-called PC3000-DDR4-RAM do not only increase the clockspeed and the voltage, they also use slower timing settings (17 as compared to 15, 36 as compared to 35). Looking at an excellent review of RAM speeds and their effects on the system on "Legit Reviews", I concluded that most likely, by going from 2133 to 3000, in excess of 50% (estimated) of the gain from the higher clock speed would be equilibrated by the slower timings.

I have therefore discarded the idea of using the XMP speed. It will make them run hotter, it will wear them out faster, and it will have nearly no effect on the overall system speeds (see the above review). Apparently the CPU cache catches most RAM access, so the RAM speed is not that important anymore.

If you want to clock them to the XMP settings, check in the BIOS what those settings are (if it shows them) and then set them manually. And if they are too far away from the Jedec settings (like 1.65 volt), then refrain from doing it. 1.65 seems very high, IMHO

Dude said:

I would set the voltage and timings manually. Does your bios show multiple xmp choices or just to enable it?

There were two settings, the 2400 and one step higher.

papa2jaja said:

I use an Asus H170 Pro Gaming mobo, which shows the XMP and Jedec settings of the RAM sticks, but there are no changed CPU settings displayed. I do think that no CPU settings should change, when the memory settings are changed. I would also guess that if you switch from Jedec to XMP, the voltage gets increased to 1.35 rather than 1.65. Have you updated the mobo BIOS to the latest version yet?

I have seen on my system btw, that the XMP settings of my so-called PC3000-DDR4-RAM do not only increase the clockspeed and the voltage, they also use slower timing settings (17 as compared to 15, 36 as compared to 35). Looking at an excellent review of RAM speeds and their effects on the system on "Legit Reviews", I concluded that most likely, by going from 2133 to 3000, in excess of 50% (estimated) of the gain from the higher clock speed would be equilibrated by the slower timings.

I have therefore discarded the idea of using the XMP speed. It will make them run hotter, it will wear them out faster, and it will have nearly no effect on the overall system speeds (see the above review). Apparently the CPU cache catches most RAM access, so the RAM speed is not that important anymore.

If you want to clock them to the XMP settings, check in the BIOS what those settings are (if it shows them) and then set them manually. And if they are too far away from the Jedec settings (like 1.65 volt), then refrain from doing it. 1.65 seems very high, IMHO

I am afraid, it did change other stuff, and this caused the computer to fail (black screen). Did not expect that, and tired as I was, I did not check before I clicked OK. Had done the same on my Z170 computer, and there only timings changed, so I did not expect any surprises. I will have to do it manually.

One aspect puzzles me. When I select XMP, it shows me the settings, but nothing is really changed yet. That usually, as with all settings in the BIOS, should only occur when you click on Exit and Save. You should have all the time in the world to read the settings because your BIOS should not make any changes before you click on Exit and Save .

papa2jaja said:

One aspect puzzles me. When I select XMP, it shows me the settings, but nothing is really changed yet. That usually, as with all settings in the BIOS, should only occur when you click on Exit and Save. You should have all the time in the world to read the settings because your BIOS should not make any changes before you click on Exit and Save .

I should have yes, but it was in the middle of the night, and having done this with the other computer without problems, I just clicked exit and save and OK. Got a short glimpse of the settings changed when exiting.

Late night sessions are the enemy of success ;-) Good luck with changing those settings and getting the best out of your RAM!

Did it again and now it worked just fine.