Zaxxan Posted January 8, 2011 Share Posted January 8, 2011 Hi all, I have an Antec TruePower New Modular 650W PSU in my unRAID server which has 2*22 and 2*25 amps 12v rails. Will this be good enough to power eight green drives and two 7200rpm drives? If not, how many drives will it actually power? Thanks for any advice given. Link to comment
Joe L. Posted January 8, 2011 Share Posted January 8, 2011 Hi all, I have an Antec TruePower New Modular 650W PSU in my unRAID server which has 2*22 and 2*25 amps 12v rails. Will this be good enough to power eight green drives and two 7200rpm drives? If not, how many drives will it actually power? Thanks for any advice given. I'd bet only one of the 12 volt rails is used to power ALL the SATA and MOLEX power connectors. Typically, that same rail is also use for the 24 pin motherboard connector. I was right... If you look at the manual here: http://www.antec.com/pdf/manuals/TP-650_Manual_EN.pdf you will see that 12V1 powers (20+4) main connector, Molex cable from PSU, and the SATA cable from PSU 12V2 powers 4-pin ATX12V and 8-pin ATX12V connectors for CPU. 12V3 powers PCI-E w/ blue stripe 12V4 powers PCI-E w/ green stripe So, you have 22 Amps available for the motherboard, all the disks, and case fans. Assuming 3 amps per non-green drive and 2 per green drive we get 2 * 8 = 16, 2 * 3 = 6. Total needed by the disks = 22 amps. If you add in a few fans, figure you need 25 amps just for the disks and fans, without adding the needs of the motherboard. Your projected load is probably near 30 Amps on a power supply rated for 22. Sorry... bad power supply for your projected use. Fine for a gaming rig with power hungry PCIe video cards and a single disk or two, but not for an unRAID server of any size. Joe L. Link to comment
Zaxxan Posted January 8, 2011 Author Share Posted January 8, 2011 Joe, thanks for the reply, It's bad a news as I bought this PSU for the unraid server because it had very good reviews. Can you take a look at this PSU to see if it would be suitable, I think it has a single +12v rail that can supply 40amps. Would this be OK? I don't want to buy the wrong PSU again http://www.overclockers.co.uk/showproduct.php?prodid=CA-147-AN&groupid=701&catid=123&subcat=1088 Link to comment
Joe L. Posted January 8, 2011 Share Posted January 8, 2011 Joe, thanks for the reply, It's bad a news as I bought this PSU for the unraid server because it had very good reviews. Can you take a look at this PSU to see if it would be suitable, I think it has a single +12v rail that can supply 40amps. Would this be OK? I don't want to buy the wrong PSU again http://www.overclockers.co.uk/showproduct.php?prodid=CA-147-AN&groupid=701&catid=123&subcat=1088 It is a much better match for your projected needs, it would power your projected 10 disks plus some room for growth as well. Link to comment
Zaxxan Posted January 8, 2011 Author Share Posted January 8, 2011 Hi Joe, I have looked into this a bit further to see if it is possible to avoid buying a new PSU. If I scale down my plans for my server to the following do you think that my current PSU will be OK? 2 * Seagate LP 1.5TB = 2*2A = 4A 5 * Western Digital 2 TB = 5*1.75A = 8.75A 3 * Fractal Design Fans = 3*0.06A = 0.18A = 12.93A I don't have any expansion cards and I understand that the CPU 12v is taken from another rail so this leaves 9.17A for the motherboard & onboard GPU, the GPU is a HD 3000 which I think uses about 30watts (2.5A). Also, the Over Current Protection kicks in at 40A. So I think in theory that this PSU should be OK, what do you think? Link to comment
Joe L. Posted January 8, 2011 Share Posted January 8, 2011 So I think in theory that this PSU should be OK, what do you think? You used more accurate numbers for your specific drives. Yes, it looks like it will work... And it looks like you know how to do the math. Now, with a non-stock (custom) cable you could tap into the PCIe rails for 12Volts, and get the +5 from one of the other molex connectors and have the other 2 12 volt rails available for disks rather than being wasted. They are not usable as is only because they dont have +5 volts needed by the drives. A custom cable could fix that. Link to comment
Zaxxan Posted January 9, 2011 Author Share Posted January 9, 2011 I think I will keep my server as a 7 drive unit and as you suggest make a custom cable if I decide to add additional drives. Realistically 7 drives will probably last me a year or two anyway. Link to comment
Zaxxan Posted February 6, 2011 Author Share Posted February 6, 2011 Hi Joe, I thought I would update you on this, I plugged one of the supplied molex leads into the red sockets 12v3 and 12v4 and tested the voltages, both of these sockets output 5v as well as 12v , also above the sockets it says PCIE and HDD so it looks like this PSU is suitable after all. Link to comment
Joe L. Posted February 6, 2011 Share Posted February 6, 2011 Hi Joe, I thought I would update you on this, I plugged one of the supplied molex leads into the red sockets 12v3 and 12v4 and tested the voltages, both of these sockets output 5v as well as 12v , also above the sockets it says PCIE and HDD so it looks like this PSU is suitable after all. Looks like you don't need a custom cable to tap the 5 volts from somewhere else. Good find. And good luck with your server. Joe L. Link to comment
Zaxxan Posted February 6, 2011 Author Share Posted February 6, 2011 The supplied molex cable when plugged into the 12v3 and 12v4 sockets outputs the 5v and the 12v as can be seen in the photo so as you say no custom cable is required, I've tested on a hard drive and it works fine. so all of the modular sockets are capable of supplying hard drives on this PSU. Good find. And good luck with your server. Joe L. Thanks! Link to comment
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