Author Topic: tony's dual power supply f.a.q's  (Read 55708 times)

joan2

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tony's dual power supply f.a.q's
« on: May 26, 2003, 09:46:51 AM »
q : why dual power supply?

a : generic power supplies are those that came bundled with the casing and as such are

    made of cheap parts and or construction quality is of the so so variety.

    as such they seem to fail to deliver power stated on their labels. this is specially

    obvious when used in amd athlons and geforce4 video card combinations. i have seen

    a 300 watt psu with a filter choke on the 3.3volt rail burned out and another not only

    burned out but also desoldered itself out of the circuit board, while in another the

    5 volts rectifiers shorted out. the power supply simply can not hack it. this is not to

    say that generic power supplies are bad, it is just a matter of derating the psu to be

    able to use them safely and thus avoid psu failures. having said those, to answer the

    question, dual psu is intended as a cheaper alternative to buying an enermax or a hec

    psu which costs 5 to 8 times that of a generic psu.



q : i used two 300 watts atx psu, so now i have 600watt psu?

a : no, this is not about simple addition, we must remember that we don't know the

    true capability of the psu in the first place, but  the saying "two heads are better

    than one", is applicable here.



q : i used a 300 watt psu for my mobo and 200 watts for my peripherals, why is my system

    still unstable?

a : if you are using athlons and geforce4ti video cards and plenty of pci cards, then a generic

    psu even at 300 watts rated is not enough. i have seen many 300watt psu wherein construction

    is very simmilar to a 145watt psu made by astech. 300watt psu such as "lanlon" is a good

    example of a capable 300watt psu. so if you are now using a 300 watt psu and can use your pc

    but with minor stability issues or if you have many add-ons like fans, two or more harddisks,

    then a 2nd psu can help your pc system.  



q : is it safe to use dual power supply, will my mobo burn is case something goes wrong?

a : dual psu when implented correctly is not less safe than using a single power supply.

    the atx design specs has enough safeguards and is supposed to shut down your psu in case of

    overvoltage/overcurrent conditions occuring at the output and undervoltge in the input, some

    psu's even went to the extent of incorporting an overtempterature cut off sensor to shut down

    your system in the event of overheating of the psu. so which psu have these features? it is hard

    tell unless we can open up the psu and look, or test them...more often than not, it is the psu,

    not the motherboard that gets fried.



q : how do i implement dual psu for my pc?

a : there are many ways to implement a dual power supply arrangement for your pc.

    you can 'google' for dual psu and the web offers many choises. i have enumerted some which i

    have tried on my own:

    1. two atx psu's with one acting as master and the second one slave, both psu's

       are not altered in any way. to power on the two units simultaneously, an extender

       device is used, the master's 20 pin header connects to the mobo in the ussual manner

       while a 4pin molex to 20pin female header is used to connect to the slave psu, the idea

       is to short the pin14,(PS_ON) to ground, a relay can be used for this purpose, but a

       simpler way is to use an npn transistor switch in leiu of the relay.

    2. an atx/at psu combo with the atx supplying the mobo and the at psu supplying the

       peripherals like hardisks, optical drives, flopies, fans, etc...



q : what is a cd-rom psu?

a : an atx or an at psu is modified to fit inside a cd rom casing, the object is to be able to

    fix the 2nd psu inside the pc casing, on the 5.25 drive bay, or even the 3.5 inch drive bay.



q : what type of power supply to use for a cd rom psu?

a : although an atx psu is possible to use for a cd rom psu, i preffer the at type since we only

    need the 5 and 12 volts rail for peripherals, and a 200watt at psu is sufficient in most cases.



q : how does your cd-rom psu operate?

a : since the cd rom psu is tapped into the main atx psu, power is applied to the cd rom psu once

    you plug in your pc to the wall, immdiately a standby 5 or 12 volt is available regardless of

    your pc being up or not, this is usefull if you want your fans running even after you power

    down your pc, a relay is used to turn on the 5 and 12 volt rails to sychronize them with the

    coresponding rails on the main atx psu.



q : how do you attach the cd rom psu to your main atx psu?

a : there are two connections, one is a 220volt power tapped into the atx 220volt receptacle inside

    the main atx psu, and the other is a 4pin molex to turn on the 5/12volts rails thru a relay.



q : how about heat, does this cd rom psu add heat inside the casing:

a : to get an idea of the heat that can be produced by the cd rom psu, let us consider the following

    loads, cd rom at 25watts, cd writer at 25 watts, two hardisks at 22 watts, ten case fans at 2 watts

    each for a total 104 watts, assuming an efficiency of 70%, then 44 watts is lost to the cd rom psu

    and this is in the form of heat. considering that an average cdrom casing has a surface area

    of about 120 square inches, then assuming perfect heat transfer from psu to  cd rom casing,

    then we are talking 0.37 watts per square inch, not very significant? consider further that

    with the exception of the fans, the rating for the harddisks and cdrom/cdrw are peak values,

    they will be lower at idle so expect the 0.37 figure to be lower most of the time.

Offline glezah

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tony's dual power supply f.a.q's
« Reply #1 on: May 26, 2003, 10:06:14 AM »
can i only use a psu that is fitted to a cdrom bay? i mean single psu lang to ha. would it be sufficient for my athlon rig?



--

hdd.

nforce2 with all the bells and whistles.

combo dvd-cdrw

--

Offline slide

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tony's dual power supply f.a.q's
« Reply #2 on: May 26, 2003, 10:13:58 AM »
i use my rig often for audio recording.  will there be a chance that the dual cpus create a ground loop hence cause hum in my audio?

joan2

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tony's dual power supply f.a.q's
« Reply #3 on: May 26, 2003, 10:24:41 AM »
slide,

grounding the psu case and the cdrom psu casing to your pc casing helps a lot. since you are not getting speaker power from your pc and i presume you don't have low-level input devices such as microphones and vynil disk pickups connected directly to your pc...the chances for a ground loop imho is nil...the only thing i can think of that may pose a problem is if you use acrylic casing...but no there are no high current devides with analog signals that may induce ground loop...i am also into construction of high power amps for audio and i am familiar with ground loop problems, but this is for another site, another thread...



glezah,

that is possible, i have one prototype in my shop right now, to bad i do not have digicam for pictures...

Offline Klay

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tony's dual power supply f.a.q's
« Reply #4 on: May 26, 2003, 12:05:33 PM »
OT: hey hardware team! anyone pick this up? good content here...

joan2

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tony's dual power supply f.a.q's
« Reply #5 on: May 26, 2003, 05:00:54 PM »
keep your questions coming and i will try to find answers...

Offline geode

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tony's dual power supply f.a.q's
« Reply #6 on: May 26, 2003, 06:26:19 PM »
Quote
... a standby 5 or 12 volt is available regardless of your pc being up or not, this is usefull if you want your fans running even after you power down your pc ...


this is very interesting specially for those concerned with their temps.  even when the pc's off it's still cooling down.  would it be advisable to connect the hsf to this psu so that even if the pc's turned off the cpu's still being cooled down.  in my opinion that's better than ung biglang mawawala ung cooling ng hsf in the usual setup.



[/quote]

Online lahar

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tony's dual power supply f.a.q's
« Reply #7 on: May 26, 2003, 06:33:15 PM »
Quote
a standby 5 or 12 volt is available regardless of your pc being up or not, this is usefull if you want your fans running even after you power down your pc




i think this is also possible via the Wake on LAN feature of the mobo.

Offline slide

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tony's dual power supply f.a.q's
« Reply #8 on: May 26, 2003, 10:01:01 PM »
ala turbo timer?  he he



joan2

thanks!  i use a low-z preamp for my mic.



ot:  since you're also into audio,  is there a chance you can rig me a low power class A zen amp?  tube would be preferred but a solid state unit would be fine

joan2

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tony's dual power supply f.a.q's
« Reply #9 on: May 27, 2003, 07:41:34 AM »
lahar,

yes it is possible to use the wake on lan feature although it uses the 5volts standby, there is such a device on the web to run your hsf fans even after your have shut down your system...

slide,

i am familiar with nelson pass' zen amps, i have plans for the aleph5 classA amp....i am a big fan of marshall leach of georgia tech, i built several of his low tim double barreled amps,around 30 units, rated at 250 watts way back late 80's to early 90's, that was before i went overseas as an OFW...

unico diablo

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tony's dual power supply f.a.q's
« Reply #10 on: May 27, 2003, 07:49:08 AM »
Sir Joan2 so far so good on your modified psu. Question though:



I have AXP 1800+ DLT3C overlocked to 2.4 Ghz running on 1.70 vcore. According to my mobo's manual, i should be able to select up to 1.80 vcore. But i'm only seeing till 1.70. There's also an overvolt jumper that i can enable. Tried using this feature but Bios is saying i'm still limited to 1.70 max vcore. Is it my psu that's hindering me from getting a higher vcore option?



Also, i checked on the actual vcore output as read by Motherboard Monitor and BIOS. It says my vcore is only 1.60. Is this a result of my psu?



My 3.3 volts rail also says i only have 3.18. Is this within a tolerable level? Hope to learn from your expertise again.

joan2

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tony's dual power supply f.a.q's
« Reply #11 on: May 27, 2003, 07:53:03 AM »
those of you contemplating on running a dual psu, here's a tip to find out if your current 300 watt psu can pass for a dual psu set-up:

1. connect psu to mobo with the all the pci and agp video cards and memory modules installed.

2. boot your system, if successful, go into bios and see if you can work on it, then power down.

3. connect a floppy drive and a hardisk, then reboot, if you can finish scandisk routine then your psu if a good candidate for dual psu....

joan2

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tony's dual power supply f.a.q's
« Reply #12 on: May 27, 2003, 08:10:44 AM »
unico diablo,

you are still within spec on your 3.3volts, lower limit is 3.13, upper limit is 3.46, motherboards are not intended to be overclocked, that's what the mobo manufacturer's officially say, but they add features that helps overclocking because there is a large segment of computer enthusiasts out there who wants to get the "biggest bang for the buck". i am not familiar with your mobo, if you are not having stability issues, then your

psu is still ok...there are instances wherein you have to trick your bios to seeing a 1.7 vcore with an actual vore of 1.8...i suggest you google this to find out more..with abit boards this is a piece of cake....

ridleyscotch

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tony's dual power supply f.a.q's
« Reply #13 on: May 27, 2003, 08:26:29 AM »
what about the avr? do u need to replace it if u are going to do a 2 psu setup?

joan2

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tony's dual power supply f.a.q's
« Reply #14 on: May 27, 2003, 08:48:01 AM »
not really, i never used those avr's i don't see a need for it. psu's and monitors operate over a wide range of input ac voltages...what i recommend is the use of line tamers, or line conditioners, to remove transients, spikes and other line garbage, both from within and without of your rig...

Offline nhald

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tony's dual power supply f.a.q's
« Reply #15 on: May 27, 2003, 09:15:54 AM »
joan2, I sent PM. hope you could answer soon. Tnx.

Offline crash_n_burn

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tony's dual power supply f.a.q's
« Reply #16 on: May 28, 2003, 01:49:39 AM »
im currently using an enermax 300watts psu. im using to power 4 hds, 2 fans, gf4mx440 wit crystal orb fan, cdrom, cdwriter, hd cooler with 3 small fans, hd rack with 2 small fans, pinnacle dv500 video editing card, raid controller, floppy drive and sb live value.im planning on adding more fans , a cathode light and probably another HD. will ur cdrom psu power them up? is my psu stable for a 2nd psu? will my pc be stable with the 2nd psu? im using my pc for video editng and it being stable and reliable is a must. how much does the cdrom psu cost? where can i purchase it if ever? thanks

joan2

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tony's dual power supply f.a.q's
« Reply #17 on: May 28, 2003, 07:52:58 AM »
crash_n_burn,

your system can definitely benefit from the 2nd psu, if you have a spare 5.25 drive bay then you can install one. you can divert some of your load such as floppy,cdroms, cdrw, hardisks and fans to you 2nd psu unit.

Online lahar

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tony's dual power supply f.a.q's
« Reply #18 on: May 28, 2003, 09:00:20 AM »
OT:



crash_n_burn,



ouch, di pas ba sumasakit tenga mo sa ingay ng mga fans?

joan2

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tony's dual power supply f.a.q's
« Reply #19 on: May 28, 2003, 12:39:33 PM »
i have ten fans inside my casing...tolerable naman yung noise....