DigitalN. Posted June 7, 2004 Share Posted June 7, 2004 k, its a mid sized case, and i was wondering if it was possible to have a second 300Watt PSU for the video card, CD roms and the fans. if i short out these pins: (thanks to Koolance.com for the picture) and just flip the switch at the back of the PSU when i want to turn off my PC, will it work? also, the second PSU would be modded into the bottom of the case Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/ Share on other sites More sharing options...
gizmostripe Posted June 7, 2004 Share Posted June 7, 2004 Im no hardware expert but AFAIK if you have one on your Mobo and thats turned off the normal way. The fan/CD drive PSU should be fine (it also allows you to run the fans after the system is off, cooling the CPU as they dont go instanstly cool after you turn off :p) unsure about the GFX card though. Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2236878 Share on other sites More sharing options...
Inertia Posted June 7, 2004 Share Posted June 7, 2004 yes it will work, you can also build or buy a relay circuit that is powered by a molex from psu1 , so that when psu1 cuts off it breaks the curcuit in your diagram above and turns offf psu2 automagicaly, and the reverse when turned on Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2236980 Share on other sites More sharing options...
DigitalN. Posted June 7, 2004 Author Share Posted June 7, 2004 Inertia: could you please point a link that i can buy one? (in canada) Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2236993 Share on other sites More sharing options...
markwolfe Veteran Posted June 7, 2004 Veteran Share Posted June 7, 2004 To avoid problems with different potentials, you will also need to connect both of the grounds (0 Volt) lines together. This way both power supplies have the same reference. Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237022 Share on other sites More sharing options...
DigitalN. Posted June 7, 2004 Author Share Posted June 7, 2004 markjensen: would it pose a problem if i didnt do that? Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237024 Share on other sites More sharing options...
Inertia Posted June 7, 2004 Share Posted June 7, 2004 I dont have much experiance buying PC parts in Canada ;) hence difficult, heres one you can get in the uk ( a review of it) : http://www.moddin.net/review.asp?ReviewID=34 heres a guide to making your own if you have an electronics components store or auto store or scrap yard , or dead car you cna get a decent relay from (the guide seems incomplete, but you get the idea : http://www.unique-hardware.co.uk/article.a...t=2ndpsu&Page=1 heres more info on building your own : http://www.hardwareanalysis.com/content/topic/27400/ I think youre best option is to make your own from a relay out of a scrap car tbh, I cant find them for sale in canada Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237044 Share on other sites More sharing options...
Inertia Posted June 7, 2004 Share Posted June 7, 2004 DaCoOlNeSs said: markjensen: would it pose a problem if i didnt do that? ide say it might well do, also it possibly might not, but it definatly wont if you do as he said, good advice Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237050 Share on other sites More sharing options...
markwolfe Veteran Posted June 7, 2004 Veteran Share Posted June 7, 2004 Well, each power supply is making a DC voltage based off of AC, so the 0V DC reference is somewhat arbitrary (based on the transformer and other circuitry in the PSUs). So, PSU #1 will put out 0V and 12V, and PSU #2 will do the same thing, but without the same 0V reference, there will be a voltage potential difference between "like voltages" on the two power supplies. This could be millivolts, or it could be a full volt. You will set up current flowing between the two power supplies (similar to connecting one battery in a loop to feed another battery - bad). It is called a ground loop, and can cause minor problems. Possibly big problems. While it may work in any individual case, it will cause problems (including equipment damage) in other cases. I would not chance it. Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237075 Share on other sites More sharing options...
DigitalN. Posted June 7, 2004 Author Share Posted June 7, 2004 but if all it is powering ios fans and crappy CD drives, would i be OK? Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237167 Share on other sites More sharing options...
markwolfe Veteran Posted June 8, 2004 Veteran Share Posted June 8, 2004 DaCoOlNeSs said: but if all it is powering ios fans and crappy CD drives, would i be OK? If they didn't share an electrical connection back to each other (the ribbon cable), I would say you would be 90% fine (just worry about the metal casings on the drives being screwed to the metal frame of your PC case. However, they have to communicate, so need to have a 0V reference passed between motherboard and drives. Gets more chancy there... :unsure: I still highly recommend running a wire between the two grounds. :yes: Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237800 Share on other sites More sharing options...
glexp Posted June 8, 2004 Share Posted June 8, 2004 Here's a link that describes the power connections: http://www.pcguide.com/ref/power/sup/parts_Motherboard.htm You must connect the commons (grounds) between PSU's. As someone else mentioned in this thread, all voltages are referenced to a common return. That common return needs to be just that ... common. :) Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2237914 Share on other sites More sharing options...
DigitalN. Posted June 8, 2004 Author Share Posted June 8, 2004 OK thanks guys, i guess I'll just go buy a 600Watt PSU instead :laugh: Link to comment https://www.neowin.net/forum/topic/175336-is-it-possible-to-have-two-psus-in-1-case/#findComment-2238214 Share on other sites More sharing options...
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