Motherboard PCB Layer vs Memory Overclocking

Author Eric Lo on 19 February, 2019 | Print | Bookmark

Motherboard PCB Layer vs Memory Overclocking

Reference: https://www.youtube.com/watch?v=r_5IwHRMwsE&t=1s

Note. 

This is just a personal summary from the video and it does not represent MSI or Toppc


A lot of people think whenever they enable Intel XMP, the memory will overclock to certain frequency according to the profile. However, this is not true because XMP (Extreme Memory Profile) only holds 5 or 6 parameter including DRAM voltage and frequency. For those parameters that are not included in XMP, it will depend on motherboard vendor to do some minor changes in order to allow the memory running stably according to XMP. 


Let’s take Intel Z-series motherboard as example, usually it has Dual-Channel and 4 DIMM slots which is called 2 DIMM per channel (ex. Z390 GAMING PLUS). If the motherboard only has 2 DIMM slots, we call it 1 DIMM per channel (ex. Z390i GAMING EDGE AC). 


2DIMM per channel (Traces: Daisy-Chain or T-type layout)


1DIMM per channel


The differences between 2DIMM/1DIMM per channel board in term of memory overclocking is that since 1DIMM does not have a fork type trace end at DIMM slot area, it has less signal interference. When signal is transmitting in such high frequency, little discrepancy would cause a huge impact to system stability. This is why motherboard vendor like MSI invests many hours in finding the best layout design to go with memory. 


** 1 DIMM per channel board has better memory overclocking capability comparing to 2 DIMM per channel board.


Besides this, the PCB layer number also plays an important role in memory overclocking as well.  


You may comprehend PCB layer number as the followings, 

If you have more PCB layers, you have more room to implement the trace in different PCB layer to avoid signal interference. For example, if you have a 4 layers PCB motherboard, the trace on PCB can only go through top and bottom PCB layer, engineer must implement the trace line to be very long so the trace would not cross each other. Of course it is not ideal for signal transmission since the goal is to minimize the trace length and reduce signal interference. As a result, it is understandable that 6 or 8 PCB layer would have better memory overclocking capability, too. 


DEMO (over spec overclocking – attempting to overclock XMP 3600 RAM to higher frequency to show the OC capability between 1/2 DIMM per channel board): 

Video 4:50 ~ 10:00

(Same Memory, Same Settings, 1 DIMM vs 2 DIMM per channel board)

1 DIMM per Channel -> Easily overclock to 4400MHz


2 DIMM per Channel -> OC fail when attempting 4000MHz



When it comes to memory vendor internal sorting, a discreet memory vendor would try to use 4 PCB layer motherboard as the baseline to validate the memory. This would ensure most of the motherboard in the market are capable of running the memory according to the XMP. If a memory vendor use 1 DIMM per channel or 6 PCB layer motherboard for internal validation, we could expect it become a mess once the memory is released to public. 


In short, if you’re an average user who just wants the memory to run according to stock XMP with more memory capacity, it is fine to purchase relatively low tier motherboard (PCB 4 layers).


If you’re somewhere in the middle who is looking for large memory capacity and decent memory overclocking capability, it is better to get at least mid to high tier motherboard (PCB 6 to 8 layers) 


Lastly, if you’re an OC enthusiast who wants to push the memory to its limit but do not care about memory capacity so much, it is highly recommended to purchase 1 DIMM per channel motherboard. 


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Last updated on 19 February, 2019 with 3941 views