2 vs 4 RAM modules which is better?

[jumbojosh]

With a dual-channel Ryzen motherboard, is it better to have two RAM modules of the same size or four to populate all slots out the gate?

 

https://pcpartpicker.com/product/TtPgXL/asrock-x570-pg-velocita-atx-am4-motherboard-x570-pg-velocita

 

 

 

 

[MarvintheParrot]

5 minutes ago, jumbojosh said:

With a dual-channel Ryzen motherboard, is it better to have two RAM modules of the same size or four to populate all slots out the gate?

 

https://pcpartpicker.com/product/TtPgXL/asrock-x570-pg-velocita-atx-am4-motherboard-x570-pg-velocita

 

 

 

 

Dual channel --- cheaper

Quad channel -- more expensive, VERY MINIMAL performance jump from dual channel.

 

Performance will also depend on the rest of the system, what is your system and what RAM modules are you considering?

[WhitetailAni]

Just now, MarvintheParrot said:

Dual channel --- cheaper

Quad channel -- more expensive, VERY MINIMAL performance jump from dual channel.

Quad channel is only available on X299/TRX40.

AM4/LGA1200 is dual channel, no matter how many sticks of RAM you have.

 

Anyway.

 

For Ryzen, you can't really run 4 sticks of RAM past 3200 MHz. So unless you need lots of RAM or you have a 3200 MHz kit (like me - I plan to get 32GB and just drop in an identical 3200 CL14 kit), get 2 sticks instead of 4.

[-rascal-]

One slight disadvantage with 4x DIMMs is lower max DRAM OC, or XMP might not work out-of-the-box.

You may need to *manually* fine-tune the DRAM (e.g. voltage and/or timings) to get it working above DDR4-3200 / 3400.

Some lower quality boards may even refuse to run DDR4-3600+ with 4x sticks.

Because 4x DIMMs puts more stress / load on the CPU's Integrated Memory Controller (IMC) vs 2x DIMMs.

This applies to both AMD (AM4) and Intel (LGA 115x and LGA 1200).

 

That is why some OC SPECIFIC boards only have 2x DIMM slots.

Example:

• EVGA Z390 Dark
• ASUS Maximus XI Apex
• ASUS Maximus XII Apex
• (Older Gigabyte Z97X-SOC Force LN2)

[manikyath]

2 dimms, so you can upgrade down the line without having to toss dimms in the garbage.

[Lord Nicoll]

I think some explaining on quad rank, dual rank and single rank is needed, and daisy chain and T topology for the memory traces is also needed. Almost all boards now use daisy chain topology for connecting the DIMM slots, so populating all 4 DIMMs on a daisy chain board will clock lower regardless. The next thing is ranks of memory, if you run 4 DIMMs of dual ranked 4Gb (gigabit) memory (each RAM chip is 4Gb, 1/8 of 4GB), which are 8GB, you'll have quad rank dual channel 32GB, which would be harder to run than 2 DIMMs of single ranked 16Gb, being 16GB DIMMs with 8 memory modules on the DIMM instead of 16 modules on each stick, with 32 modules per channel. The more ranks you have vs a given speed and timing, the more performance you get for those settings, however they're harder to run, so there is a trade off. There are many DIMM PCBs that effect this too, and many difference ICs and sadly, knowing what works best with specific ICs is needed to be able to overclock them effectively on a given platform. 
Running two single ranked DIMMs in the same channel will make that channel run in dual rank mode also, I should have explained that too. Basically a rank is a set of a specific number (in this case 8 ) modules that are in the channel. If you have 2 groups of 8, it's dual ranked, 3 groups of 8 it's triple ranked, however this is a gross over simplifaction of this to make it easier to understand. Ranks are not channels but just how the memory is organised in a channel. 

Despite both being 32GB, the first one is a lot harder to run just because there are more memory modules attached to the IMC, and is a reason why early DDR4 clocked sorta bad, I have a 32GB kit of 4Gb Micron MFR, meaning 64 memory modules, it is insane to think these kits existed as it really does clock like arse. Best I got was 2800MHz, however this memory is also a bad bin as it's only 2133MHz, doesn't even have an XMP profile, despite being Corsair LPX.
 

T topology boards are a little different, in order to get these to clock the best, all 4 DIMMs (assuming a dual channel, all 8 DIMMs if quad channel) must be populated otherwise there is RAM traces going to random pins that are open to the air, thus acting as antenna. These boards aren't as popular now as they where, but should still be watched out for as you can have a bad time trying to OC just two DIMMs on these. 

[freeagent]

Are you guys just running stock voltage settings? 

 

I can run 4 sticks up to 1900 no problem, and I am a noob wtf guys