no need to be puzzled by why Dell spec says 2666 while using 3200 ram.  what can be relied on is user validated data.  You do not have to buy Dell ram.  Just look for ram that exactly matches user validated ram for 5400 on eBay UK.  e.g., (1)  HMA81GS6DJR8N-XN 1x8GB[IMAGE] [URL] (2) HMA82GS6DJR8N-XN 1x16GB [IMAGE] [URL]
Good Day Everyone! I apologise if this has been asked before but I can't seem to find a definitive answer on the boards, so here goes! I wish to upgrade my memory on my current system which is:    - Dell Inspiron 24 5400 AIO - 8gb Hynix (OEM) DDR4 3200Mhz RAM, Intel i5 - 1135G7 (11h Gen)[NAME].40Ghz. I am not able to buy Crucial RAM at 3200Mhz as they are out of stock.  I can buy the RAM at 2666Mhz.  I won't buy the Dell RAM as it is way overpriced. My configured clock speed (using WMIC) is 2666Mhz but the speed of the RAM shows 3200Mhz.  The Dell user manual states 266Mhz RAM for my system. Will it be ok to use the Crucial 266Mhz RAM in my system (2 x 8GB) or must I use 3200Mhz RAM (which is what Dell initially installed). Thanks for your help.  
MEMORY UPGRADE - INSPIRON 24 5400 AIO