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Some of the power savings could be chalked up to less RAM, because more RAM requires more power. But that doesn't explain all the results. Is there a calculati
by 0cf8612b2e1e 2y ago
Some of the power savings could be chalked up to less RAM, because more RAM requires more power. But that doesn't explain all the results.
Is there a calculation to estimate RAM power consumption? I keep wanting to get a low powered N100, and have been wondering if I use say 8 vs 16GB RAM, would that make a measurable power difference?
- Mistletoe 2y agoA small amount. > As a rule of thumb, you can expect to allocate around 3 watts of power for every 8GB of DDR3 or DDR4 memory.
- 0cf8612b2e1e 2y agoSimilar for DDR5? In the context of a N100, 3W is actually pretty high. Many of these systems idle around 10W.
- flyingpenguin 2y agoYeah but unless you are deploying a bunch of them, its only like $3/year each
- snovv_crash 2y agoThat's why many laptops run LPDDR these days.
- spockz 2y agoMy N100 from minisforum runs on 3.6W idle with 4-8W for medium to high cpu usage to 20W on full load with SSD, CPU, and integrated encoder loaded. It is way more powerful than a pi and in low power mode as efficient.
- fswd 2y agoI probably have the same N100 miniforums and can only get it down to 7w. Is it possible you could share how you got it down to 3.6W and 4-8W? I just got this N100 a few weeks ago, have it on a killawatt next to my desk.
- spockz 2y agoThere are many tips here: https://gathering.tweakers.net/forum/list_messages/2096876 https://gathering.tweakers.net/forum/list_messages/2096876 but I think the thing that did the trick was simply `powertop —-auto-tune`. I also disabled the wifi in the bios. I ran for a bit with turbo disabled which lowered the consumption a tiny bit and severely limited the peak usage, but it also made the system slow overall. So I enabled it again and now sometimes usage spikes but feels snappy. I’m running Fedora.
- AshamedCaptain 2y agoI have a ASUS PN40 and I got it to idle at 1.8W just by installing a Linux distro with almost no tuning whatsoever. (Just installing tlp which was at the time part of the suse laptop metapackage).
- mallets 2y agoThat's a ridiculous amount of power, is that answer from a LLM? It's in the range of ~150mW for LPDDR4. Around half that in idle.
- hnuser123456 2y agoYou specified LP, they didn't.
- mallets 2y agoIt doesn't matter too much whether it's LP or not for idle, around 20% more at worst. It's at full BW util where it's close to double power consumption. That would still put it at less than half watt for full load. Look for "AM62x Power Consumption" app note, page 5.
- adgjlsfhk1 2y agohttps://www.servethehome.com/ddr4-dimms-system-power-consumption-tested/ https://www.servethehome.com/ddr4-dimms-system-power-consump... which is the only source I've seen that looks even vaguely trustworthy gives 2 watts per 8 gb of ddr4 (and ddr5 should be about 10% lower since it drops to 1.1 from 1.2 volts assuming similar amounts of current).
- hajile 2y agoTheir numbers seem to indicate that Pi disabled parts of the chip in firmware instead of physically lasering them out. This leaves those parts still leaking some current and explains the power difference.
- moffkalast 2y ago> 8 vs 16GB RAM, would that make a measurable power difference? I think the short answer is.. it depends. Current draw depends on usage, supposedly from 10% at idle up to full when doing massive read/writes. But it should be in the two to three digit miliwatt range which isn't much compared to the N100 itself which pulls 6W at idle, being an inefficient x86 space heater. The Pi 4 4GB can idle at 1W using LPDDR4, the Pi 5 8GB using 50% more efficient LPDDR4x idles at... 3W. Meanwhile the average 12GB LPDDR5X Android phone can idle a whole week on a tiny 1 cell lipo (with power saving mode on), making this look so bad it's actually funny. The long standing problem with Pi Foundation products is a complete disregard for any low power states, sleep or hibernation, so they probably don't do any RAM related power optimization either. It's only now with the RP2350 that they've finally implemented some kind of working sleep mode for the very first time in anything at all.
- Marsymars 2y ago> N100 itself which pulls 6W at idle That's not right - my entire N305 system takes 4-5W at idle.
- moffkalast 2y agoFair point, N100 systems do differ quite a bit generally, the numbers I've got in my head are what I've seen people quote for the Radxa X4 recently. Some might be more, some less.