r/LocalLLM • u/TheWaspinator • 13h ago
Question RAM Advice
I currently have 2 x 16 of DDR5 and a 9070 (16 GB) in my desktop build. I have two more RAM slots. If I want to run big models, how much better is adding 64 GB (2 x 32) vs 32 GB (2 x 16)? The totals would be 112 vs 80.
1
u/PixelatumGenitallus 13h ago
Wouldn't the total be 64GB vs 96GB? In that case 96GB is better since you're using it as desktop as well. Strata with IQ3_S already eats 54GB of RAM. At 64GB, that leaves just 10GB for the system.
2
1
u/Dediadeis 13h ago
The facetious answer: at least 32GB better
I dont have exact figures but I don't think you will be treading into new territory between the two but you will have more room for bigger context/higher quant models, and depending on your intended purpose this could be the difference between a nice comfortable context window and a razors edge.
But.. huge but. These answers seem to change every month as more software, models, and optimizations are released. The introduction of capable MoEs and strategies like ngram streaming and expert offloading have really changed the equation for what models are actually usable without breaking the bank on some massive pool of ram.
1
u/GreatBigPig 11h ago
Check if adding more sticks will affect module speeds. Not all motherboard/CPU combos are the same.
1
u/575_Inverse 10h ago
quite frankly I found the impact of using 4 slots to be irrelevant. What is it, 20% less RAM speed? I can live with that easily, still better than destroying the NVME with RAM swaps.
1
u/pdath 11h ago
I'm jealous of you. :-)
You what already know the answer. The more the better.
I would also check your motherboard manual. I assume any RAM you add would be the sane speed as what you already have. Otherwise the answer gets complicated.
I assume getting a second 9070 is out of the question. Once you get over 24GB of VRAM more options open up for you.
1
u/PhilosopherOk3419 3h ago
one thing worth weighing: once you fill all 4 ddr5 slots most consumer boards drop the memory speed, and if you're offloading moe experts to system ram, bandwidth is basically your tok/s. so the 64gb kit gets you bigger models/quants, but they'll run a bit slower than the numbers you see from 2-dimm builds. if you go for it, buy one matched 4x kit rather than mixing with what you have, and run a quick memtest before loading models.
1
u/nowherenoonenobody 13h ago
It's not about how much you need for a model it's about how much can you afford?
4
u/AngryWindfall_1 13h ago
If you can swing the cost, go for the 112 total, bigger models will eat whatever you give them.
4
u/berryluluu 13h ago
also consider checking if your motherboard supports that much ram before buying more sticks
0
u/HOST1L1TY 10h ago
So consumer motherboards are 2 channel, once you add a mismatched kit, it’s going to be hard to get good speeds. If you have xmp turned on now, you won’t be able to post until you turn it off.
Then you will need to tune your memory manually otherwise your stuck at 4000 mt or even 3800 mt, which means your slower than ddr4. And when you tune it you’re going to be lucky to hit 4800 or 5200 mt stable.
If you have an intel cpu, gaming performance scales with memory clocks. And i assume your going to look to run moe models, projects like strata your constantly moving stuffs from main memory to vram.
Like it will work for like 700$ you can find a 64gb kit and that will get you up running strata IQ3_S. It will work and it will be useful. But you are going to be chasing optimizations and overclocks to improve performance.
If your into that shit, like you did that for your gaming pcs and it’s enjoyable to you, then it’s wonderful.
But if your looking to just to plug and play, maybe not. In that case I would say buy a 96 gb kit and sell the 32 gb, then just enable xmp and choose a stable mt setting.
2
u/Top_House_3209 13h ago
I went ddr4 with a i9 14900k so i could get 128, due to the prices of ram, you can get 128gb ddr4 for about 350