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Using 2 PSU's at once QUESTION

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June 22, 2006 5:34:52 PM

Hi, I am planning to build a new system either by the end of summer or maby in the begining of 2007 the build will probably include the folowing:
-17.1 inch LCD MAG display
-2 HD
-2 Optical drives (CD-RW, DvD Drive)
-Floppy drive (or not, considering theyr becoming obsolite)
-AUSU Core2 Duo capable Motherboard ( still not shoor which one to pick)
-Core 2 Duo processor probably the 2.18 Ghz or maby the 2.4 wersion
-ATI's Radeon x1900xt GPU (or one of the new dx10 gpu's that will come in 207 if ill be building the system then, im planning to spend max $400 on the gpu)
-ATI tv tuner card, the 650 theatre chip one
-2 Gigz of ram DDR2 667 (most probably)
+ a thermaltake fan controller and 7 in case fans (80 mm each)

Now for the question:
I have now a Thermaltake Purepower 480W PSU (with a absolute max output of 550W) will this PSU will be enough to power this system? I also have another 360W PSU which i replaced for the 480W one, Would it be possible to use 2 PSU's? that is lets say the 360W one for the GPU and the other to power the entire system? I just got the 480W PSU about a year ago, and to be honest i do not want to buy another one, the one im using now (480W) woks fine now , and I never even had it get warm at all(even at a full system load/gaming for max 3 hours or so) If it is possible to use 2 CPU's at once is there any specific way I should connec tthe 20(or 24 pin connectors? both psu's come with 20 pins but i got a 24 spliter for the future mobo)

I know that there are mini cpus for graphic cards sold at present, that install into the frontal drive bays, but honestly i would prefare to awoid buing a new psu, having thise 2 work fine so far. but to be honest i would like to use the psu's that i have available to me at the moment( if it is possible)

P.S. Does anyone know of any external power supplies that I would be able to connect my gpu to ? somthing like the AUSU 1900 i think had, an external minipower converter unit, this aproach woud be the best
Thank You for all replies.

More about : psu question

June 22, 2006 6:14:18 PM

The Thermaltake you have should be fine. If it isn't, then the best solution is to buy a new PSU.

There are ways to run two power supplies, yes. You can buy an external PSU, but they're really expensive and tough to travel with.

Or, you can use two regular PSUs, short out your auxiliary PSU using a method you can google (because I don't know it), then put both of them in your case.

However, this method is best used if you'll be using a case that can hold two PSUs. The Cooler Master Stacker can do it, as well as the Lian Li PC-G70. I would go with the G70, personally.
June 22, 2006 6:47:15 PM

Based on the specs you have listed your peak demand would be 450w based on this psu calculator

http://www.extreme.outervision.com/psucalculator.jsp


Try out the 480w and see if it works. If it doesn't then there are 3 ways to get both psu's to start. you can put one psu on a switch to the front of the case (any 4 pin 12v switch will work), you can use a relay from a 4 pin molex of the main psu to start the secondary psu or you can splice the green "power on" wire from the 20/24 pin mb power connector of one psu to the other and any two ground wires.

Instructions on how to do the 3 choices above can be googled and I'll not recreate some nice instructions that have already been written. btw, buying a nice 750w psu will cost less than either of the cases suggested in the previous post.
Related resources
June 22, 2006 6:51:27 PM

thx for the inforamtion, im using the thermaltake Xaser III series case

here is the link to more info on it and pics
http://www.thermaltake.com/xaserCase/xaser3/v1000d.htm

maby I'm mistaken but isnt the Lian LI a Btx type of case, im using a atx one , i think i might have a bit of space for the other older psu inside on the same "railing" on the top , althou there is one fan mount there which might vlock the instalation a bit, but i check the auxiliary PSU info, thx
btw in regards to the external psu's i was just wondering are there maby ane psu cases so i could place my psu in , and connect the power cables to teh pc's case?.... maby this is a wild idea..but i was just curious.

thx
June 22, 2006 6:55:19 PM

thx for the info ill check it out, so afar as the cases go im planing to stay with the one i have now, i like it, and besides its only 1 year old ;)  lol and it has a quite nice ventilation system ( i mean the placing of the fans is nice , 2 frontal 2 on back , 2 on the side and 1 on the top)
June 22, 2006 7:08:46 PM

1 more question, is the Surge Compensation and the Capacitor Aging very important? in the calculation of the psu power usage? the psu i have has a bit more than 1 year i would say maby a bit less than 1.5 years and more than 1 year. should i change the values in the chart? or should i ignore those? ( i susually use the pc for max 14 hours max other days maby around 10 hours) and its most of the time in idle, other times i just use ms office or use it for entertaiment
June 22, 2006 7:22:01 PM

The capacitor aging and surge compensation won't be too big of a deal. You start having problems with that after a couple of years usually, but not after only a year and a half, especially with that amount of usage that you say. At least that has been my experience.

Another thing: you mentioned not having a floppy due to its being deprecated. I say that is a good idea. However, you may want one (internal, external, it doesn't matter) lying around just in case you need to use it. It may be something that you don't need most of the time, but when you need it, you NEED it.
June 22, 2006 7:23:01 PM

btw i read the info about the amperage of teh psu info on the calculators site, my psu has only 18A mps and the ati's site states that 30A are needed but isnt that for crossfire? im not planing to run a dual gpu system, will those 18 A be enough?
June 22, 2006 7:25:55 PM

The aging can be an issue but I usually just take the base value and add 20-25% and you're usually safe. As to using your current case, it's a nice one, I have the armor and I may be using a dual psu system in the future as well. My water cooling took my 600w to the limit...

Make sure you use a good surge protector or ups to plug your computer into for safety.

Also, if you use a 2 psu system make sure all the core components are on the same psu, mb, cpu and video card. Voltage differences, even minor ones, between two different psu's can cause damage for anything that is plugged into the motherboard. Run your hdds, optical drives and fans off the second psu. If you aren't using some sort of connection between the main and secondary psu (to start the secondary one) make sure you power on the secondary one first so that the hdd's are running before you give power to the core components.

18 amps is a little low but you won't know until you try it... take all the components that run off the 12v rail and add up the power then divide by 12 to get the amps.... 20-24 amps is probably the minimum you want even without sli/cf.
June 22, 2006 7:28:25 PM

More than likely that's for crossfire. If you are just running the GPU on the PSU, the Amp rating can be a bit lower, as it isn't powering anything else, and can direct all its energy into that one thing.
June 22, 2006 7:33:01 PM

thx for the info and in regards to the floppy drive i agrie, im using one now and i was planing to use the same one later on, but i havent ben using it at all for a long time and came to a conclusion that taking it out will save a bit (a very small bit :wink: ) of energy and ill have a bit more space in the case, and in case of the need i would plug it in, the only problem i might have is to find a nice motherboard that has support for core 2 duo (with possible crosfire support, i might use a lower end gpu for calculating phisix, but i have no plans for that, and by that time i think i would get a new psu...hopefully) and also i will be using 2 hd's which are IDE and similar with the dvd and cd rw drive connections, and as far i noticed that ASUS ofers (the P5wd2-e Premium) mobo but it lacks support for core 2 duo :(  besides that i was planing to buy that mobo but now that i will be geting the core2 duo cpu i m im searching for a different motherboard.
June 23, 2006 2:06:18 AM

Thank you for the information, I was planing before to use the weaker 360W psu for the gpu, and teh 480W for teh rest of the componetns, but now i realized that that wouldnt be the best thing to do (thx to Your post) so ill probably use the 360W one for powering those 2 wd, 2 optical drives (floppy optional), the fan controller, and the fans

Thank You again for the valuable information.
June 23, 2006 3:25:06 AM

dunno if anyone mentioned this. but will 2 PSU's fit in that case?
!