August 19, 20187 yr 8 hours ago, John_M said: 5.00 volts - 4.95 volts = 0.05 volt = 50 mV, which represents a 1% drop. How is that even significant when it is so much smaller than the tolerance on the rail voltage anyway? Excatly - 4.95V is excellent. The ATX PSU specifications that all computer equipment manufacturers are required to design for allows 5% regulation or 4.75 - 5.25 V and allows up to 50mV top-to-top ripple. So a HDD/SSD that doesn't work well with this input is considered non-compliant and it's time to return it and get the money back. But connecting a large number of disks to a single cable could result in undervoltages or too large ripple because of the voltage losses in the cable. And could also result in too high temperatures in the PSU connector for modular power supplies. Same with the PSU itself - if it can't manage to be within the ATX specifications for any load within what the PSU datasheet claims, then the PSU is considered non-compliant.
August 19, 20187 yr Author My extended smart completed without issue. And file integrity finished without finding anything corrupted. My first feeling is I’ll plug the next lot of drives into new cables directly from the power supply assuming when I reach the Psu limit it will turn off. but given the data provided here, my startup power draw on these Red and Seagate NAS disks is quite a bit lower than calculated. There was room for it on the rail. Sounds like i need to keep 4 disks per cable from the power supply seems to be the thing here. I’ll see how i go with the next 4 drives i put in, it won’t be till October-November when ill order them. If i can’t power them up with the rest of the drives, then i know i’ve reached the limits of the power supply or run into read errors on multiple drives during a preclear that seems pretty obvious what their problem will be. My case is rather large being a Core WP100 i do have room for a second PSU. But it seems clear here the “best Psu” is the one with the most power allocated on 3V+ and 5V+ section. It seems 10 Hard Drives are budged for on these Consumer PSU’s and pushing 20 may be possible but clearly not recommended. After much reading on NAS forums, it is recommended to not exceed 12 Drives to a consumer PSU. The 3V+ and 5V+ rail is not designed for that level of power draw over 12 Drives. The other recommendation was a 750Watt or 850Watt PSU since they have a 150Watt 3V+ 5V+ allocated to them. Look at specs for a PSU that has that allocated to them, not to purchase a cheap power supply because it was cheap given when the blow up the hard drives usually get destroyed in the process. I have found the below plug that can easily allow me running two PSU’s for this server. https://www.scorptec.com.au/product/Power-Supplies/Accessories/69884-AC-005-CNONAN-P1 Edited August 19, 20187 yr by Maticks
August 20, 20187 yr @Maticks Sound good no problem now. I like you found some comment not power-up more then 12 drive by consumer PSU. Recently I swap HWs to a 2U/3U case, it come will a cheap PSU (but still a 80 plus with 3.3+5 DC-DC design). Due to need quiet, so I mod it and found the DC-DC cost reduce so much. So sometimes we playing fire.
August 20, 20187 yr Author The answer seems to be 75W is allocated to 3V and 75W is allocated to 5V, the closer its running to that limit the more degradation is done to the PSU. recommendations seem to be average operation should not be exceed 80% with startup spike not really being an issue provided it doesn’t trip overload protection. @John_M Mentioned it would be 55W on the 5V rail with 20 Drives. I guess that would be the absolute maximum possible... anything over that will trip overload protection for sure. Thankfully these NAS drives don’t have high power draw on startup like some of the enterprise drives. The cost of 4TB drives is still better over 8TB disks hence i’d rather buy more disks over bigger disks. Scaling didn’t seem to be an issue when i started i assumed SATA Drives would pull from the 12V rail and i have plenty of 12V given its a single rail and built for consumer PCI Express graphics. I completely forgot about the 5Volt rail all together, if only there was a card of device that i could plug a 12V PCI Express cable into and it split out Sata power for me that would be awesome.
August 20, 20187 yr 7 minutes ago, Maticks said: The answer seems to be 75W is allocated to 3V and 75W is allocated to 5V, the closer its running to that limit the more degradation is done to the PSU. No, the source were from 12v, and combine means total not more then 150w, but still limit by spec. amper. 10 minutes ago, Maticks said: I completely forgot about the 5Volt rail all together, if only there was a card of device that i could plug a 12V PCI Express cable into and it split out Sata power for me that would be awesome. Sure, there are many standalone module/device, typicaly a DC to DC, but need DIY skill.
August 20, 20187 yr 9 hours ago, Maticks said: The answer seems to be 75W is allocated to 3V and 75W is allocated to 5V, the closer its running to that limit the more degradation is done to the PSU. The specifications for the PSU can be found here: https://www.corsair.com/corsairmedia/sys_master/productcontent/corsair-psu-spec-table.pdf The PSU can give max 150W combined power from 3V3 + 5V. And it can give up to 25A on 3V3 (=82W5) And it can give up to 25A on 5V (=125W) So if you load 5V to the max, you get 25A and 125W, and you will have max 25W left (7A5) for 3V3. But you need figures for how much the motherboard requires from 3V3 and 5V, and you need to take into account how much 5V is loaded by connected USB devices.
October 2, 20187 yr Author upgraded to a HX750i and pushed the USB header into a VM on Unraid to get corsair link working. This is my peak usage when i run a disk check it spikes to this load on the 5V, well under the 25A.
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