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dead lcd display and cpu fan

i just finished building a system for a friend. i've run into a problem and hope someone can lead me in the right direction.

the case is pretty cheap and flimsy and the quality isn't great. instead of taking my advice and buying a decent psu, my friend said he'd like me to use the one that came with the case. i wasn't comfortable about it, but hey, it's not my $.

here are the specs:

el cheapo psu: voltage 115/230v - +5v & +3.3v combined load 230w, +5v, +12v & +3.3v combined load 422w, total output is 500w max.

asus a7n8x e-deluxe
amd 3000+ athlon
2x512 geil ddr400 pc3200
gf fx 6800 gt 256mb
sndblaster live! 5.1
wd 80gb 8mb cache sata
wd 80gb 2mb cache ide
dvd rom
dvd rw

here's what happened.

everything was working great. got windows installed, updated. i even loaded my copy of doom 3 to test the temps and how the system would handle it in general. for several days in a row, i booted it up, played around with it, tweaked some settings, etc. and all was ok.

i had just finished calling him to let him know it was ready. he asked if i could put the hdd (the ide one) from his old system into this new one. i told him i would, but that i didn't feel comfortable about that psu.

i installed the 2nd hdd. i don't think it had much, if anything to do with that in particular, and i'm still not convinced that the psu was the culprit, but 2 or 3 minutes after i booted it up with the 2nd hdd, the cpu fan and the lcd display on the front stopped working. needless to say, i shut it down.

the wires coming from the circuit board up front are controlling the power button, the reset button, the lcd display, a set of lights on either side in the front, and the cpu fan.

the only two things not working are the lcd display and the cpu fan. this leads me to believe that the circuit board is ok, but maybe the other connections short-circuited.

my first thought was to check the wires and make sure they were plugged securely into the motherboard - and they were.

i know next to nothing about troubleshooting this type of problem.

anyone have any suggestions? i'm just not sure where to begin.

i can post pics if it'll help.

thanks. :)


Political User
First thing you can try is rechecking all your PSU connections... also use yoru sniffer, smell the PSU itself. Try changing it (if you have one). Just a matter of trial and error till you find whats wrong. Try taking out that HD you put in, stuff like that.
Assuming there is no burnt smell...

Disconnect his cheapo PSU and put your PSU in. Try and power up. If everything comes up his supply could not handle the system.

500W should be enough but - WATTS means nothing anymore Due to increasing power demand you need check the amperage available at each voltage.

The 6800 and the AMD 64 need lots of 12V power. The new power standard is ATX 2. It requires 2 independent 12V power supplies in the PSU. Check if it is ATX 2 and if it has 2 seperate 12V outputs.

Post how much 12V capacity the cheapo can supply. It should be 18A on each 12V rail (that's 36A total) or a total single 12V output of at least 30A.

If you keep putting 1 pound weights on a table the legs will eventually fold. The HD may have been the "last pound". It could have as easily been a new optical drive, another stick of ram, a new case light, etc.

Are there any other lights ON? Keyboard, optical mouse? Do the case fans turn? etc.
the cpu is a 32-bit, not 64, btw.

i failed to mention that (it's been a long week) one of the first things i did after this happened, was to unplug that 2nd hdd. it was my first assumption that the psu couldn't handle all the components. that made no difference. the system would work fine without it hooked up, but the cpu fan and the frontal lcd display were still dead.

i did try and smell the front section of the case, as well as the psu. i couldn't make out any burn smells whatsoever.

the system will boot up and operate normally, even with the 2nd hdd hooked up. i'm almost positive i could plug the cpu fan into an outlet on the mobo, and it would work.

but that doesn't really solve the lcd display on the front not working.

the case has 2 neon-like lights along the front of the case that run vertically on either side from top to bottom. there's a button on the bottom that controls the power to those lights and they work.

yes, case fans all operate normally, as well as lights on the keyboard and optical mouse. like i said, absolutely everything works on this system - except for the cpu fan and lcd display.

i'm out of town tomorrow, but will return on sunday and plan to take your advice and try the psu out of my gaming rig (a rock solid enlight 420w). i'll let you know how it goes.

thanks for your suggestions. keep 'em coming! ;)
Oh, never mind the PSU. The 500W PSU is ok if that much is working.

(Sorry I missed the Athlon 3000, duh, not reading carefully.)

Most likely when you put the second HD in:
1) You knocked off a wire going to the LCD.
2) The molex power plug you used on the HD may have a pushed back pin. Those power connectors are cheap to begin with and with a cheap brand they get even worse. Try a different power plug on the HD.
3) The CPU fan not spinning has me stumped. The CPU should overheat and the MB shut down really fast if the CPU fan does not turn. Are you positive it is not turning. Do not run the comp if the fan is not turning!

I just read more carefully...
The CPU fan is not hooked into the MB??? IF it's plugged into the LCD and the LCD controller is not working the fan won't turn.

Plug the fan into the MB for now to keep from frying the CPU!!! If the LCD starts working then that fan may be overloading the LCD controller.

If the LCD doesn't work check the wiring to the LCD I'll bet it got knocked loose installing the HD. Or the 2nd HD case is shorting out the LCD.


hardware monkey
did you have Qfan enabled when the cpu fan quit? if so, try disabling it and see if it goes then. sounds like the board has a 5v problem.

Son Goku

No lover of dogma
Depending on the load of that CPU fan, you might need to plug it directly into the PSU, rather then the head on the mobo. I think the CPU fan that comes with my current fan/sink (it's an OCZ Gladiator II or something like that) comes with a fan, where it was indicated the power draw is too much for the connector on the mobo. They advised against using it, though my fan also came with a 5.25" molax type connector...

Try plugging it directly into the PSU (you might need a 2-1 splitter to plug this in there, best to put it on a lead with another case fan, rather then a drive IMO). You might need an adapter for this. I know the Delta fan I have lieing around here has such an adapter which takes the type connector that would plug into a mobo (the Delta does draw too much current for that though) and allows it to fit in the 5.25" drive connector, so they've got to be around.

If you can connect this to the PSU directly, and it spins, then the lead for it on the mobo might be burnt out. If that's the case, leave it connected through the PSU. They'll lose fan speed monitoring, but if it might have burned a lead off the mobo for it already...

The the PSU fan still doesn't work, get another. One shouldn't go running that there CPU without a fan...

As to the power LED, if it's properly connected and the connector wasn't shaken loose, about all I can say is "well it was a cheap case". I'm not sure if those can be replaced (as I have never needed to, even in my current case which is about 5-6 years old and has run pretty much 24/7). Never had one burn out, to try... Perhaps someone else knows whether you can or not...
ok, i'll try and answer the questions, one by one, and also let you know what i did.

1) checked the psu and yes, it does have 36a.
2) correct - the cpu fan, power button, reset button and lcd display are ALL connected to the mobo
3) qfan is disabled in the bios

ok, here's what i tried.

i disconnected the cpu fan connection coming from the lcd display in front. i connected it directly to the mobo, and as i suspected, it works. i simply was trying to get the lcd to display that the cpu fan was spinning and at what rpm.

i know that leaving the system running while the cpu fan is not working isn't a great idea, and that's why i turned it off after a couple of minutes. also, this mobo (the exact same model i have in my gaming rig) comes with c.o.p. (cpu overheat protection) - and that feature works great on this model. anytime the cpu even thinks about getting too hot, the mobo shuts down - excellent protection there.

i disconnected the 2nd hdd power and ide cables, but that didn't make a difference. i also checked to see if the hdd was mounted too closely to the cables coming off the lcd display in front and they're not. there's plenty of space there.

i also checked to see that all the wires coming from the lcd display board are plugged into the mobo firmly and they are.

and here's what baffles me. the power and reset buttons are coming from that exact same circuit board in front that controls the lcd display, and they work!

the lcd display does not. i also noticed that the tiny hdd power light and activity light for the hdd do not work either.

so, at this point, (sorry for being long-winded) plugging the cpu fan directly into the mobo is working. the lcd display is still dead. the power light and activity light for the hdd won't come on, BUT, the power button and reset button - coming from the same circuit board as the lcd display, ARE working!

i'm truly stumped.

i have to go out of town today, but i'm planning on trying the "plug in a real psu" idea and see where that goes.

but, since i switched the cpu fan to go into the mobo direcctly, and unplugged the 2nd hdd, shouldn't the display now work if the psu was being strained?

i'll post back as soon as i can. thanks for the help.

today, i tried several things.

i got hold of another psu and tried it - no effect.

then i took out that old 2 hdd and double checked the connections. sure enough, one of the power connectors had come unplugged. i reconnected it and all is working!

but, that still doesn't explain why it simply stopped working the first time - i was staring at the desktop after windows had booted up, trying to decide what to install next, when the lcd display and cpu fan shut off.

i guess that could be attributed to a psu that's going bad or maybe it's just crappy.

oh well, at least everything is working perfectly...for the time being. ;)

thanks for all the suggestions. they really helped the troubleshooting process.


Beware the G-Man
Political User
Possibly it had a power connection, just barely. Then it lost connection when it died.

When ya pushed in the power connector at the initial install of the #2 HDD it prolly pushed the pin out. But there was just enough contact to send power through. As things warm up you got sepparation at the pin connection and then... dead. I've had a few situations when I had to pull hardware out of my box and when I reinstall there was a power problem. And sure enough, a pin will pop out and cause havoc. Worst ones are the ones when the connection is just good enough to have everything running. Then as everything warms up you get more and more resistance in those connections and it goes poopy.

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