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2 Asus motherboards fried, they run fine then die. cant locate problem.

Posted on 2008-09-30
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Last Modified: 2013-12-11
Hello. Here is the story. I purchased a new PSU, motherboard, case, and some other accessories for my computer recently. I pulled everything out of the old case, and built everything in the new case. My old motherboard was an Asus Crosshair. I purchased an Asus M3N-HT Deluxe, which I promptly installed. After about 14 hours of working properly (left it on overnight, but NOT in windows... windows would not boot it bluescreened complaining about the disk), i shut it down the next morning. it never passed post again :(
no beeps no nothing fans spin up thats it.... no beeps even with no memory... asus says its fried for sure

take it back and get a new one
new one lasts about 80 seconds and dies right in front of me... bluescreened on windows boot and then froze later on in the bios, after which it would not come back....

psu, right? i went and bought a psu tester (thermaltake dr. power.... i know, it was the only one they had). i have never used one before, but i hooked it up to my new psu (zalman 850), and sure enough, it said the -5v was bad. the stuff that came with the tester said that if a light failed to illuminate, that rail was bad. OK.
so i am sending the board back AGAIN, this time with the PSU.
so i have my old psu that worked fine before, so im thinking i can drop in my old board and old psu for the time being. i put the tester on my old psu jsut for the hell of it, and GUESS WHAT, no light on -5v. bummer. is the tester bad?? i have no idea...

if its not the psu,..... what IS it???
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Question by:evan2645
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by:evan2645
ID: 22609049
PS>> i forgot to include a couple of things that could be causing this that are non-standard... keep in mind ive been thinking about this for a long time!! lol

1. i spliced the rpm lead on one of my fan connectors with the rpm lead from my WC pump... i simply pulled the old pin out and put the pump's pin in... i thought maybe the other pin touched up against something and shorted it out so i cut the pin off the end of the lead after the first board fried... obviously that didnt help

2. i have 2 120mm fans on 1 fan header using a fan splitter. i called asus ahead of time to get the rating on the fan headers but after being escalated 4 times the guy just said "yea you will be fine"... ugh... too much load on a fan header couldn't cause something like this, could it??
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Accepted Solution

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rafter109 earned 425 total points
ID: 22609094
It certainly does sound like a PSU problem but lets cover the bases anyway. Did you perform the motherboard installation using an anti-static wrist strap or any other method to prevent static discharge into the motherboard or other components? If you did use one, then double check to ensure that no metal from the case comes into contact with the traces on the motherboard. The only place that contact is acceptable is where the motherboard has designated holes for screwing the board to stand-offs that are attached to the case. Also try plugging the computer into a UPS or power conditioner as these will alleviate peaks and sags in the supplied outlet power which will in turn ease the job of the PSU
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by:evan2645
ID: 22609205
well, i didn't use a wrist strap but i am always sure to touch the chassis before i do anything... also everything in the case looked normal the only place it was touching was the screws... additionally, both times the boards blew i had it on a 1200w ups.

linked below is a pic of the tester i bought... it is very strange to me that the -5v light did not show on either psu. could it be possible that the zalman damaged it too? according to the documentation, all lights should come on. i know the previous psu to be good when i pulled it.

http://i00.twenga.com/p/98/61/459861vb.png
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Expert Comment

by:rafter109
ID: 22609461
For your 2nd posting:

1. This should not cause a problem as most rpm sensors are standardized. Do be sure that you are properly insulating any wires that you may have cut to be sure that nothing is shorting against them.

2. Running 2 fans on 1 fan header may or may not cause a problem. It really depends of the ratings of the components driving the header as you are effectively doubling the amp load that the headers are designed to supply. Personally, i would find an adapter to provide a fan header plug from a molex psu plug. They are cheap and abundant on the web.

One more thing about your psu: Your tester could be bad. If you have a digital multimeter you can test the rails yourself. Remove the PSU from the computer and disconnect all of its connectors from any components. Locate the large connector that usually plugs into the motherboard and short the green wire to any of the black wires while the PSU is pluged into the wall and switched on. The PSU's fan should now be spinning and the supply is ready to test.With your mulimeter set to test DC Voltage place the ground probe of your multimeter into one of the holes containing a black wire and use the other probe of your multimeter to check that the voltages correspond to the colors as listed below:

Red = between 4.75 and 5.25v
Orange = between 3.135 and 3.465v
Yellow = between 11.4 and 12.6v

If all of these voltages are within the ranges above, your PSU is probably ok. Try hooking it back up to your computer and booting it then using the Multimeters see if they are still in range. If the voltages are now out of range, you have a bad PSU.
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Expert Comment

by:rafter109
ID: 22609508
I have one of those testers too that I use in a pinch but if I have a multimeter, I always use it. I double checked on my tester and with only the motherboard connecter on it, all lights come on. If the unit beeps, one of the voltages is out of its testing range. It is very possible that the PSU is putting out more voltage on one rail that it is supposed to as some PSU's rely on voltage dividing circuits that upon failure can output the wrong voltage.Please check your PSU with a multimeter to be sure.
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by:evan2645
ID: 22609513
the reason i didnt use a molex for the fan is because i wanted to be able to utilize the qfan speed control feature on the motherboard to help keep noise down.. i much prefer it to using speedfan etc

that sounds good i will test it that way when i get home... if that passes and i hook it back up, how do i test with the multimeter after it has been installed?

the tester had a light specifically for "-5v", which was the one causing concern. would the voltage tests listed above verify that the 5v return is good? thanks for all your help
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Expert Comment

by:rafter109
ID: 22609652
I understand why you used the splitter on the motherboard but please understand that when you connect 2 of the same devices to a single power source, you double the amps that the power source must provide. Depending on the rating of the circuitry that feeds that power source, you may stress it past its capabilities potentially leading to catastrophic failure. If Asus says that your setup is ok, I would be inclined to believe them as they are accepting the responsibility of replacing it if it fails.

The -5v is testing the white wire. this should be between -4.75 and -5.25v test this one with the multimeter as well as it seems to be showing you problems.

The best way to test the psu while installed is to stick the multimeter probes into the side of the motherboard connector where the wires are coming out. It may be difficult and require a little force. It may be easier to put the probes into the connector first then install the connector onto the motherboard. If you can get the computer to boot, check the power on each color (red, yellow, orange) during boot, and if possible, under load.
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Assisted Solution

by:jamietoner
jamietoner earned 75 total points
ID: 22610242
About the -5v rail most modern power supplies don't have a -5v rail anymore(check the side of the power supply), as motherboards no longer require it. I don't use PSU testers anymore as many power supplies fail when under load and only extremely expensive testers can test the psu under load. I have had too many bad power supplies pass on these, best option is to try another psu. I personally wouldn't suggest hooking both 120mm fans to a single fan port on the motherboard without knowing how many watts each fan pulls and the max the port can handle. To control the fan(s) you could use a 5.25" or 3.5" bay fan controller, I use 2 3.5" controllers to control the 8 fans in my system.
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by:evan2645
ID: 22615501
jamietoner-
you would be correct. i checked the specs and the -5v rail is absent. i thought about getting a fan controller however i hate giving up the slots for it and i only have 3 fans on the radiator... plus i would have to run a temperature probe to the cpu which is a pain. i wish they made some kind of pci fan controller that can get temperature values from the board! that would be awesome... thanks for the input though; if i have to ever get another fan for some reason i may just do that

rafter109-
i checked the voltages and all seem to be OK.

last night i installed my old board and old psu and booted up successfully. the boards are the same manufacturer and the dual 120mm fans did fine on the one header... i know it is likely that the ratings are different, however im willing to bet that is not the problem (although, as a side note, would both of those fans be able to achieve their peak RPM simultaneously?). i believe that the psu is failing under load as you both have mentioned, however i have no way of safely testing that at this time. the psu and board are being RMA'ed today; i will be sure to post back next week when i get everything back from newegg. thanks for all your help so far
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by:evan2645
ID: 31515587
Thanks guys. Sorry for the delay; took a while to get all the hardware back. Box is up and running!
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