is 16x8 GB Ram better than 8x8?

Hello.

I have Msi Alpha 15 comes with 1x16GB 2666mhz DDR4 Ram. I have seen on youtube that 2x8 improves gaming performance a lot, like 5-8 fps on ultra settings.

Some people on the internet claim that 2x8 would work better than 16+8 even though 24GB is much than 16. But, wouldn't 16 in 24 work as 2x8 anyway, so the leftover 8 GB would just stay there? Or does it work differently?

Thanks.

 

Works differently. Dual-Channel vs. single channel. Dual-Channel is better/faster.

Ideally, you would want 32GB or higher (matched 2x sticks).

 

But wouldn't 16+8 work as 2x8 dual channel + 8 single channel? In this case, how come it has less performance than 2x8 straight. I don't get it. Is that because windows decides to use rams with different logic?

 

Yes with an additional 8GB stick, a 16GB + 8GB scenario would have dual channel mode for 2x bandwidth functional up to 16 GB of memory usage, then after that performance will drop off.

I would check that you do in fact have just a single 16GB stick. I would not expect a laptop to be sold with just 1 large 16GB stick and another empty slot.

 

It will work exactly this way. It is called asynchronous dual channel mode.

I doubt that 16GB dual + 8GB single channel will work slower than 16GB dual, at least in absolute majority of tasks. If there are benchmarks claiming it, let's discuss those. Othwerwise, these are just unsubstantiated claims.

 

Window , and therefore all programs running under it, will use all the RAM at its disposal. It does not differentiate between single channel and dual channel when it grabs what it needs.

It will be slower. Especially when it is using close to the maximum amount available when in asynchronous dual channel mode.

Even if the total RAM is equal.

The only reason to run asynchronous dual channel mode is if an identical stick of RAM is no longer available.

That is why any system I put together is maxed out for RAM as close to day 1 as possible.

Not only will the system be as fast as it can be, but the user will be enjoying that faster system for the lifecycle of the platform, and not just for the last few months of its use.

 

I have run mixed size dual channel benchmarks and there is almost never a performance loss vs fully matched dual channel as long as you are under the dual channel memory allocation limit. Hardware prioritizes lower memory addresses to be allocated first. Windows allocates virtual addresses all over the address space, but physical addresses are contiguous in the lowest address space possible.

I have even run 4GB memory sticks with their SPD flashed to say they are 8GB, and they ran windows fine until their 4GB capacity was reached (hard freeze).

 

'Almost' and 'under the dual-channel limit' is what I like to avoid.

I don't have RAM or any other compute resource to 'save' it. If it's there, it will get used.

 

Yeah totally with you. If you need more ram you need more ram. I'm just saying if what you do only needs 16GB and you already have 16GB, just getting an 8GB instead of another 16GB for dual channel to save on cost is totally viable.

 

I'm with you too. But nobody only needs just 16GB of RAM. Even back in 1823/1903, they desperately needed more.

You remember when dinosaurs were roaming the earth while the first chips were still dreams, of people yet unborn...

See:
Computer Processor History (computerhope.com)

 

We're comparing 24GB asynchronous dual channel with 16GB regular dual channel here. More RAM reduces the need to access storage in many tasks, and even single channel RAM is way faster than any modern storage device. Most tasks - except iGPU RAM allocation - don't really benefit from dual-channel RAM, difference is couple % if any. iGPU will most likely allocate dual channel portion the RAM, thus won't take a hit - and even if it did, @Tandou 's gaming laptop relies on dGPU for intensive tasks. Bottom line, performance degradation due to lower total amount of RAM is much more realistic than any possible negative impact of using RAM in asynchronous dual channel configuration, at least in this scenario.

 

It will be slower and there is still no guarantee the faster dual-channel RAM will be used, first.

But you're right. More RAM is always better.

 

Since your machine already came with 1x16GB 2666 MhZ DDR4 RAM, I'd suggest getting another 16GB 2666MhZ DDR4 RAM (as a single stick) with similar timings.

Its better for the system if your machine runs in dual-channel mode as opposed async mode... plus, 32GB is better than 24GB.

In terms of raw performance, RAM will only provide about 5-10% performance boost... depends also on timings and the kind of CPU you have.
Since you have MSI Alpha, and it likely has a Zen 2 CPU, you'd be better off getting a 16GB stick of same speed and timings (JEDEC-wise) for optimal performance.

You usually get more RAM to have more memory really (which is increasingly useful/needed when you are working with content creation and gaming), but you also want to optimize your RAM performance and Zen infinity fabric... which would work best if you had 2x16GB sticks of same speeds and timings.