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mini21
Journeyman III

Help in choosing RAM for 7800x3d

Hello everyone 

I wanted to ask for help because I was a bit I'm dumbfounded. 

I'm building a new PC based on 7800x3d (as you can see it will be a computer for gaming + some photo and video processing).

I already ordered a motherboard - I chose a B650 Tomahawk but the problem with the ram started...

I ordered two 16 GB chips - Lexar Ares RGB, DDR5, 32 GB, 6400MHz, CL32 LD5EU016G-R6400GDLA.

In the future, I wanted to buy 2 more chips of the same memory and have 4x16 GB, but... 

On another forum someone told me that combining 4 ram chips is not a good idea because 2 of them will not work at full speed

For as long as I can remember (i.e. for a very long time) it was the arrangement of 4 dice that was better than 2 pcs. - unless something has changed 

Now I don't know what to do - should I return the ones I ordered and order 2x32 gb at once (which I don't really have the funds for so far, so all the rest of the components would have to be left for a month) or leave it and buy an additional 2 chips after some time? 

And as for the ram model itself - I've read a few reviews of these lexar And they performed pretty well – while also being a little cheaper. Do you think they will be ok or do you return and take something else (they are listed on the motherboard compatibility list).

 

Please help! 

3 Replies
DipakJ27
Adept III

The Lexar Ares RGB DDR5-6400MHz CL32 RAM that you ordered is a good choice, and it is compatible with your B650 Tomahawk motherboard. However, you are correct that combining 4 RAM chips is not always the best idea, as it can sometimes cause compatibility problems or reduce performance.

If you are planning on using 4 RAM chips in the future, I would recommend that you buy a 4x16GB kit at once. This will ensure that all of the RAM chips are compatible and that they will work together at the same speed.

However, if you are not able to afford a 4x16GB kit right now, you can start with 2x16GB and then add 2 more chips later. Just be sure to buy the same model of RAM to avoid compatibility problems.

As for the Lexar Ares RGB RAM itself, I have read good reviews about it. It seems to be a good value for the price.

Overall, I think that the Lexar Ares RGB DDR5-6400MHz CL32 RAM is a good choice for your new 7800x3d PC. If you are planning on using 4 RAM chips in the future, I would recommend that you buy a 4x16GB kit at once. However, if you are not able to afford a 4x16GB kit right now, you can start with 2x16GB and then add 2 more chips later.

I hope this helps!

Dipakjadhav

Thanks. 

The general point is that (as I was told) slot a1 and b1 are slower  Because... well, I'm not going to repeat it.

Once that 4 pieces consume more energy than 2 even with a larger capacity.

To quote : "Each memory chip consumes power, so having twice as many is twice the load to the motherboard's VRMs. DDR5 is unique in that the power supply for the memory is onboard the memory itself and no longer relying on power from the CPU. 

Still, the memory controller on the CPU (or I/O die in the case of Ryzen) means that having four sticks means double the processing taking place in a small area and through the traces on the motherboard. Generally speaking this means that higher speeds are not possible. So if bandwidth is important you want the smallest number of larger sticks. If capacity is most important, you also want density. 196GB is possible using 48GB sticks, but you can expect this to be at 4800MT/s rather than a potential 6000-6400 for Ryzen

the bottom line is that four DIMMs presents twice the electrical stress on the memory controller, and thus, the CPU, as two DIMMs does. Twice the electrical stress also means, more heat, more electromigration potential, and a much higher chance of a reduction in the quality of signal integrity. Which is not to say that systems cannot utilize four DIMM configurations. They can, of course. But it is basically almost always a better choice, on consumer platforms at least, to use only two DIMMs, IF you can achieve the same desired overall capacity, because it's less stress on the IMC and it's generally also cheaper. A 32GB kit that consists of 2 x16GB is almost always going to be cheaper than a 32GB kit that consists of 4 x8GB, assuming that we are talking about a SINGLE matched set and not four individual DIMMs or two 2 x8GB kits. Doing THAT, opens you up to WAY more probability of compatibility issues among the DIMMs. That's another concern as well. The more DIMMs involved, the greater the chances that something is not going to want to "play nice together".

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Do you know what rank this RAM has?

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