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I've often wondered this -- why isn't it normal for consumer systems to support more RAM? I built a PC with 256GB DDR4 in 2016 for working with large pointcloud

I've often wondered this -- why isn't it normal for consumer systems to support more RAM? I built a PC with 256GB DDR4 in 2016 for working with large pointclouds, but most motherboards I looked at only supported 64GB max, and the situation doesn't seem to have changed in the last 6 years. I guess it's because the emphasis with RAM has been on improving speed rather than volume.

deleted 4y ago
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magicalhippo 4y ago
Were you thinking about adding more RAM slots, or why the sticks aren't larger? The reason the sticks aren't larger seems to be because they had trouble scaling down the DRAM memory cells[1] since about 2016. DRAM works, as you might know, by letting a capacitor hold a charge (or not). This ability is a function of the geometry of the capacitor: the area of the anode and cathode, as well as the distance between them. Leakage current discharges the capacitor, hence why DRAM needs to be periodically refreshed, the industry settled on 64ms retention time per cell[2]. Leakage current tends to go up when the features shrink, due to there being less insulation between the conductors. As mentioned in [1] it seems things are about to change, so perhaps we'll see much larger sticks in the near future. If you were thinking of slots, I think that's more economics and feasibility. The Threadripper motherboards had 8 slots[3], since the CPU supported it, but they were quite expensive compared to regular Ryzen motherboards. It also requires a lot more power, so forget having that in laptops. And the slots take up space, so was only for the full ATX size[4]. [1]: https://www.allaboutcircuits.com/news/micron-unveils-1a-dram-process-node-highest-density-dram-to-date/ https://www.allaboutcircuits.com/news/micron-unveils-1a-dram... [2]: https://www.csl.cornell.edu/~martinez/doc/isca13-mukundan.pdf https://www.csl.cornell.edu/~martinez/doc/isca13-mukundan.pd... [3]: https://www.asrock.com/MB/AMD/X399%20Taichi/index.asp https://www.asrock.com/MB/AMD/X399%20Taichi/index.asp [4]: https://www.asrock.com/mb/AMD/X399M%20Taichi/index.asp https://www.asrock.com/mb/AMD/X399M%20Taichi/index.asp

deleted 4y ago

[deleted]

magicalhippo 4y ago

Were you thinking about adding more RAM slots, or why the sticks aren't larger? The reason the sticks aren't larger seems to be because they had trouble scaling down the DRAM memory cells[1] since about 2016. DRAM works, as you might know, by letting a capacitor hold a charge (or not). This ability is a function of the geometry of the capacitor: the area of the anode and cathode, as well as the distance between them. Leakage current discharges the capacitor, hence why DRAM needs to be periodically refreshed, the industry settled on 64ms retention time per cell[2]. Leakage current tends to go up when the features shrink, due to there being less insulation between the conductors. As mentioned in [1] it seems things are about to change, so perhaps we'll see much larger sticks in the near future. If you were thinking of slots, I think that's more economics and feasibility. The Threadripper motherboards had 8 slots[3], since the CPU supported it, but they were quite expensive compared to regular Ryzen motherboards. It also requires a lot more power, so forget having that in laptops. And the slots take up space, so was only for the full ATX size[4]. [1]: https://www.allaboutcircuits.com/news/micron-unveils-1a-dram-process-node-highest-density-dram-to-date/ https://www.allaboutcircuits.com/news/micron-unveils-1a-dram... [2]: https://www.csl.cornell.edu/~martinez/doc/isca13-mukundan.pdf https://www.csl.cornell.edu/~martinez/doc/isca13-mukundan.pd... [3]: https://www.asrock.com/MB/AMD/X399%20Taichi/index.asp https://www.asrock.com/MB/AMD/X399%20Taichi/index.asp [4]: https://www.asrock.com/mb/AMD/X399M%20Taichi/index.asp https://www.asrock.com/mb/AMD/X399M%20Taichi/index.asp