Is mixing 1.35 and 1.4v DDR5 a terrible idea?

mid_gen

mid_gen

mid_gen

Soldato
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I've got 32gb (2x16) 1.35V DDR5 6000 at the moment, but I'd like an upgrade. I didn't really pay attention to the voltages when I built this system, but not it seems that a 32Gb 1.35v kit costs a £20 premium over 1.4v.

Would 1.35 and 1.4 play nice? Or should I just stop being tight and cough up....
 
What CPU are you running?

You may need to stop being even tighter, and buy a 2x32GB Kit, as depending on the CPU you may not get rated speed with 4x16GB regardless of voltage.
 
mid_gen said:
I've got 32gb (2x16) 1.35V DDR5 6000 at the moment, but I'd like an upgrade. I didn't really pay attention to the voltages when I built this system, but not it seems that a 32Gb 1.35v kit costs a £20 premium over 1.4v.

Would 1.35 and 1.4 play nice? Or should I just stop being tight and cough up....
Click to expand...

It just isn't about voltages. RAM IC may differ, timings may differ. Which is likely as one kit is 6000MHz 1.35V and other 1.4V.

I have in the past used two differing kits with same RAM IC/timings/voltages, did work out, but it wasn't DDR5.

DDR5 training is more complex then past iterations. I would avoid mixing kits.

Usually dimms are tested to work together, so that's why there are 4 dimm kits and people don't suggest getting two kits of 2 dimms to make 4.
 
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<grumbles something about the good old days when you just stuffed as many SIMMs in as you could get your hands on>

Think I'll just put with 32gb for now, not a problem just yet.
 
Reading a bit more.... I'm a bit peed off tbh. What the is the point of 4 slots on AM5 if you can't run more than two sticks of RAM? I bought AMD because I expected the socket to last for a while, but turns out you can't really upgrade the memory.

Should have gone Intel and stuck with DDR4 by the sounds of it.
 
mid_gen said:
I bought AMD because I expected the socket to last for a while, but turns out you can't really upgrade the memory.
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You can already get 2x48 and 2x64 is coming, so it should be feasible to upgrade into the longer-term. Future CPUs and BIOS updates may improve stability and performance.

If we reach a stage where you really NEED the 4 slots, the slow performance will be less of an issue than running out of memory, but realistically it'll be obsolete by then anyway.
 
Tetras said:
You can already get 2x48 and 2x64 is coming, so it should be feasible to upgrade into the longer-term. Future CPUs and BIOS updates may improve stability and performance.

If we reach a stage where you really NEED the 4 slots, the slow performance will be less of an issue than running out of memory, but realistically it'll be obsolete by then anyway.
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What's the actual real-world performance hit from running 4 dimms at lower speeds? Having the physical ram is more important than raw speed, and much of my workload is Gpu (I don't game much)
 
mid_gen said:
What's the actual real-world performance hit from running 4 dimms at lower speeds? Having the physical ram is more important than raw speed, and much of my workload is Gpu (I don't game much)
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If you don't need the bandwidth then realistically not a lot, best thing to do would be slacken your timings ~C36 and drop your speed to 5600, and see where you sit. If you are happy you could easily run two kits at 5600 on most CPU's, but TBH I don't know why swapping to a 2x32GB or 2x48GB kit is such a big deal, it's not going to cost you mush more if anything, and in terms of overall system cost it is ~1-2%
 
mid_gen said:
Reading a bit more.... I'm a bit peed off tbh. What the is the point of 4 slots on AM5 if you can't run more than two sticks of RAM? I bought AMD because I expected the socket to last for a while, but turns out you can't really upgrade the memory.

Should have gone Intel and stuck with DDR4 by the sounds of it.
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Even on DDR4, 4 DIMMs on dual channel board tends to be slower/tricker also.

Most boards use Daisy Chain Topology for memory tracing. Where as T-Topology (where each DIMM slot has equidistant tracing) is favourable for 4 DIMMs, but few boards use this.

cultists.network

Motherboard 101 - Part 2: Memory - Cultists Network

There are multiple ways in which memory is connected to the CPU, here you can find the basic principles of the commonly used methods.
cultists.network cultists.network

It doesn't matter if you go Intel or AMD, current or past platform, rule of thumb is 4 DIMMs is harder for CPU IMC, tricker for signalling for motherboard.

All motherboards that are geared for max RAM MHz (regardless of DRAM tech) will be 2 DIMMs slots. ASUS on some past highend boards with 4 slots, used to have setting in BIOS to turn off slots.

Even on high end platforms (ie quad channel), more DIMMs = lower attainable max MHz, timings, etc.
 
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mid_gen said:
What's the actual real-world performance hit from running 4 dimms at lower speeds? Having the physical ram is more important than raw speed, and much of my workload is Gpu (I don't game much)
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Depends on what kind of workload you do, (Puget have a recent article on this) for content creation it is anything from 0% to like.. 15%, depending on the task and the difference between the slowest speed and the top speed (like 4800 and 7200).

For gaming, it depends on the game, the resolution and where the bottleneck is, but generally similar numbers to the above. The use of an X3D CPU reduces the performance hit significantly.

For the most part, moderately fast RAM (e.g. 5600) has a very low performance impact (e.g. around 2-5%) compared to faster ram like 6400/7200, which is why I say that if you NEED the capacity, you won't care.

Running 4x32 would be a different story, because 4x dual rank sticks could drop to very low speeds (like ~4400), so the performance hit would be larger, but even then, if I needed the capacity I wouldn't be bothered by that.
 
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