The bios certainly does need to retrain if the memory has different timings/etc, esp if you're set to use an XMP profile.

I've also had dozens of times where when you first insert new memory, not all the pins connect and the system won't post.

I make it a habit now to seat the memory ~5 times whenever I'm adding new sticks.

 

The memories are identical (brand, frequency, timings, etc.) but bought in different periods. When i seated new 2 sticks, at first i thought somehing was bad placed and i turned pc off, so i tried POST with the older 2 sticks (as my system has always been) and again it took 5-10 seconds to POST with DRAM led on, so i waited more and then it started well; so I seated the new kit and i got the same thing: 5-10 seconds for POST, OS started and DRAM led faded away. So i think also the first time all the sticks were well placed, i should've waited for more time and maybe the system POST but i'm not sure. Just little worried about DRAM led red light on the FIRST start-up; usually those leds on motherboard mean hardware problem but i'm not so skilled about actual components.

Thank for your interest

 

If you are using XMP to set memory timings, disable it and manually input the timing settings.


tRFC will need to be opened up a bit to accept the new sticks most likely, as not all motherboards set this properly.


example, with the 2 original sticks, if tRFC is sitting at 350, try 450 with the 2 extra sticks installed.


you may also need to add a tiny bit of system agent voltage to deal with the extra sticks


EDIT I apparently need to make it clear for other users above, you can MOST CERTAINLY mix and match memory sticks of different brands and types.


What you will NEED to do is find the MATCHING speeds and timings, even if they end up SLOWER. Then you can start tweaking or adding small bits of voltage to get things closer together.


Mixing and matching is NOT recommended for best results. But it CAN be made to WORK. and WORK does not always mean fastest.