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Home built computer nblack screen problem

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March 25, 2011 10:29:01 AM

Asus p7p55 Lx
Intel i5 750
4gb 1600mhz gskill ram
400w ocz PSU
hd 4870 512 gfx
Samsung sata 2 500gb hdd
Maxtor 300gb ide hdd

June last year I built the above system and it has run smoothly for the whole of that period except for the last couple of months. It all started out with the occasional blue screen when booting the computer up. Reset or two later it would be fine. This may have just been a bug that I managed to take care of though, so may be unrelated.

Anyway so a few weeks ago I get a stupid ass “usb current overflow detected computer is shutting down” error. This happened everytime the computer booted up. Well after updating the bios and resetting them the error disappeared. However now instead of this error when the computer has been off for anything from 2 hours plus the computer will start to boot and then black screen.

When it does this it cannot be reset via the button on the front but the switch must be flicked on the back and when powered back on it sounds as if the hdd is booting up really slowly before displaying anything on screen which is not what it usually does basically, so I thought this could be the problem.

I however unplugged the hdd today and booted it up and the system crashed on checking nvram. After the computer has rebooted about 3 times it will not suffer any more problems until it is powered down for a number of hours. Most of the computer is also brand new and as you can imagine its driving me nuts as I don’t want to send the system back and be without a computer for weeks. I would rather smash the damn thing up at this point and order a new one no kidding. This is how much it’s annoying me.

Sometimes the computer will boot, be on for 5 minutes and then black screen I have no idea what it is as it’s not the hdd. So I thought dodgy ram possibly however I haven’t bothered doing a memcheck on it as my old system had a bad stick of ram was crc erroring all over the shop yet passed a 24 hour test on that piece of *** program that is memcheck.

What could this be or do you think I’d be better off smashing the piece of crap up?

Some other things to note i doubt is the PSU as when the system is powered on its fine for hours without a single crash for example i was playing Crysis 2 on full spec last night for about 6 hours no crashing nothing.

Id would really appreciate anyones insight because to be honest i haven't got a clue whats causing this problem.
a b à CPUs
March 25, 2011 12:52:23 PM

Black screens are typical of graphics card issues. The 4870 used to have leds on them and will tell you the type of fault it detected...and they are power and temp related faults. Check those first - should be 5 leds next to each other. Google it.

Because Crysis2 runs doesnt mean anything...if anything causes a fault then you have an issue.

And while your system isnt particularily power hungry, that 4870 is.... 400w should cover you but it is nagging me a little. Any chance you have another PSU around to swap in and try??
March 25, 2011 5:37:09 PM

havent no but ill be doing some tests tomorrow when i can recreate the problem.
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a b à CPUs
March 25, 2011 6:10:36 PM

(1) On memory check. Recommend Prime95. I find it much better at identifing memory errors and generally much quicker than memtest86

(2) On PSU. What I would do is download/install/Run CPUID HWMonitor. The Voltages (primarily the +12 V may be close to the lower limit inwhich case a spike my trigger it. While running it start up Prime95 an not the min values for your voltages. On the +12 V min is listed as 11.4, myself I replace if min is 11.6. Might as well verify temps while there.

However I would suspect the GPU, above are just to rule them out.
March 26, 2011 12:24:25 PM

Heh i have now solved the problem and it was ever so simp0le and imagine someone facepalming bigtime.

faulty keyboard

I'm well made up it isnt anything more serious, it must have been sending a short to the computer. With a different keyboard it booted first time no black screen and know like spaker bang you know that noise that speakers make when you first plug them in well i was getting that on startup and that has now also gone. really shuffed.

Thanks for the replies guys always appreciate the time from you dudes and further thanks to that PSU tip something ill be using in the future and will test next as 400w is a bit close but had the idea of replacing it when upgrading the graphics which is soon.

I bloody love this forum there are gems of reads all over it.
March 26, 2011 1:35:38 PM

The keyboard sending short to the pc copuld this cause damage to the motherboard?
a b à CPUs
March 26, 2011 7:02:55 PM

Yes it is possible for a keyboard to "Kill" the port that it is plugged into. All depends on the malfunction.
I had a keyboard that wipe out the PS2 port (quite a while back).
Sounds like your OK as everything works fine after replacing a keyboard.
March 27, 2011 1:38:42 AM

good to know and thanks again.
!