Light on MB but no power to rest of computer

September 19, 2010 at 02:49:02
Specs: Windows XP Pro SP2, P4 3.4ghz / 2gb DDR2
Morning! When I press the power button on my tower nothing happens - absolutely nothing - doesn't make any noises, doesn't attempt to start, doesn't even make an "electricity flooding in to the system" type noise. When I first started to figure out what was wrong, I was all set to swap the power cable for an identical spare, but then I noticed that the small green LED on the MB was still on. It goes out when I flick the switch on the back of the PSU to off, and comes back on when I flick the switch to on, so power is getting to the machine through the cable, but maybe not enough to actually turn the computer on? Just done very basic check of internal cables, to make sure power button on the front of the tower is still connected to the MB, and nothing else has come loose - can't see anything untoward, although there is the faintest burnt smell inside the tower. Got a hunch it's going to be the PSU, but thought I'd run it by you guys first? What do you reckon? The PSU is about four to five years old, and has been fairly stable up till now. My computer does generally run a little hot, but when I put it to standby last night before going to bed, it was all working fine. Any ideas?

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#1
September 19, 2010 at 03:08:24
Pull the powersupply and see if the burnt smell is coming from it. If you are lucky only the PSU will have failed. The fact you see a motherboard LED means little. A PSU provides power in several different voltages and any of those can fail independent of the rest of the unit.

On a side-note, it isn't recommended to use standby in a desktop/tower system. Standby was created specifically for laptops. Turn your system off overnight.

Goin' Fishin' (Some day)


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#2
September 19, 2010 at 03:33:33
Yeah Richard, PSU is definitely the cause of the slightly burnt odour. I use standby occasionally, just because the desktop has annoying habit of turning itself back on after I've shut it down; the number of times I've got myself snuggled down in my warm comfy bed, only to hear the tell tale beep of my desktop turning itself back on! I swear it's got a mind of its own somedays!
Cheers for advice re: PSU. Will take HD out and magicbridge it to laptop so I can still get work done today, and maybe head to local computer repair shop tomorrow after work. I built the system myself a long time back, and it's always been a little "special" e.g. running hot, turning itself on and off etc - might be time to just hand the whole lot over to the repair shop, and tell them to sort it once and for all!

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#3
September 19, 2010 at 04:08:43
Having the light come on means that one part of the power supply is working. I just replaced a power supply that had a similar condition. The 5v SB bus was working but nothing else. I swapped a new similar power supply and the system fired up OK.

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#4
September 19, 2010 at 04:39:37
That's reassuring to hear wizard - fairly confident based on my own knowledge and the responses on here that the PSU is the guilty party - now just got to decide whether I just get the PSU sorted, or whether I splurge and do a full on upgrade to the MB and CPU whilst I'm at it - my 3.4ghz isn't so bad, but hankering for something dual core (any recommendations?) and whilst I don't do the gaming I once did, I'm doing more and more video editing and graphic design - maybe time to upgrade the video card too! Cheers again for the response.

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#5
September 19, 2010 at 05:11:29
Sorry I can't recommend any upgrades. I usually get my computer from broken hand me downs. This last computer was a 3.0 GHz P4 with 160 GB HD but only 512K ram.

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#6
September 19, 2010 at 07:26:51
Don't skimp on the power supply. Buy a reputable name brand unit & plan on paying $50 or more, unless it's on sale or a rebate is involved. Here's a good deal on an Antec 520W unit. It's $60 upfront but after using the $10 off promo code & rebate, the final cost is $35:

http://www.newegg.com/Product/Produ...


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