x2 iMac PSU to power GTX 1070    - Page 1
Forum section: electronics / general

author: deadmanwalking
author_rank: Newbie
timestamp: November 17, 2019, 08:28:06 pm
content: I have a external GTX 1070 GPU "EXP GDC Expresscard beast" connected to a Lenovo T540p for render with Lumion, I power the GTX 1070 with a standard ATX PSU, all cables and components loose and exposed, so to carry it into a backpack with the laptop I want to enclose all the components into a case, and smaller the case, more suitable to carry around will be. SFX are ridiculously expensive in my country (USD$200 and more), if I try to import one, the mere shipment cost be too expensive to even consider it.After looking around I came with the idea of get an iMac PSU to power the eGPU, I can get them NEW for cheap and shipment is very reasonable, adding the benefit of smaller size compared even to a SFX PSU, I'm planning to use a Apple iMac 21.5" 2009-2011 A1311 205W PSU 614-0444 661-5299 that is enought for the 180w the GTX 1070 needs, but if in the future I want to upgrade to a more power demanding GPU, the 205w can be not enought (besides, I'm sure not all the 205w can be delivered in the same 12v rail), so the question come here: can I get x2 PSU to feed a single GPU?Thanks in advance for the advice and comentaries

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 17, 2019, 10:29:28 pm
content: Could you get a HP 460W server PSU for cheap?

author: wraper
author_rank: Unknown
timestamp: November 17, 2019, 10:33:22 pm
content: Quote from: NiHaoMike on November 17, 2019, 10:29:28 pmIf you want to became deaf from jet engine noise.

author: deadmanwalking
author_rank: Newbie
timestamp: November 17, 2019, 11:39:00 pm
content: Quote from: NiHaoMike on November 17, 2019, 10:29:28 pmI have a couple of that PSUs laying around, but are too heavy and noisy for the purpouse, I need a light/small alternative (I don't like external bricks neither)Quote from: wraper on November 17, 2019, 10:33:22 pmThe iMac PSUs are virtually fanless, another benefit, but can I plug a pair of them like they where AA batteries in parallel?

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 18, 2019, 02:54:42 am
content: The 460W PSU, if it's the same one I have, is pretty quiet even under load. The 750W and 1200W can get noisy with a heavy load, but a single GPU is not going to push those very much. (Those are obviously heavier than the 460W and thus would not be my first choice for that application. I did use a 750W for my external GPU setup until I got a 460W to replace it.)I wouldn't recommend paralleling PSUs unless they're designed for that purpose with provision for load balancing.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: November 18, 2019, 03:00:24 am
content: Quote from: deadmanwalking on November 17, 2019, 11:39:00 pmSo the question is can you take a GTX 1070 GPU, two 'virtually' fan-less power suppliers engineered for an iMAC and stuff these in as smaller case as possible?Physically Yes......

author: BradC
author_rank: Super Contributor
timestamp: November 18, 2019, 03:53:12 am
content: Quote from: deadmanwalking on November 17, 2019, 11:39:00 pm"Virtually fanless" ?? The iMac has several fans and there is actually quite an airflow over the PSU even at the lowest fan speed.And no, you can't just whack the power supplies in parallel.

author: deadmanwalking
author_rank: Newbie
timestamp: November 19, 2019, 01:50:51 pm
content: Quote from: blacksheeplogic on November 18, 2019, 03:00:24 amI know phisically it can be done, but is there any constriant into joining two 12v lines from different PSUs?Quote from: BradC on November 18, 2019, 03:53:12 amI know they aren't really fanless, but they are cooled from the air moved inside the case by the CPU fan, not from a dedicated fan (that's why I used the term "virtually"), and anyway I planed to use a 80mm or even a 120mm fan to cool these PSUs if necesary.Why can't join a couple of PSUs? just to know the thecnical reason, I'm very curious