Power not coming on but left unplugged overnight it-

[gasman336]

started right up. This is a DELL Dimension 5100 with a 3.2ghz, 1.5 gig ram, with a 305 watt power supply. So here I bought this unit from a private person. He had to load up some software and I asked him to power it up and off when I was there. I got there yup powered up working finished loading nero up then logged off and turned off the computer with no problem waited a few seconds hit the power button - nothing would come on green light on the motherboard waited for the green light to go out after uplugging it opened it up check connectors all tight figured bad switch. Couple hours later starts up no problem take it home plug it in .. yup start right up try to hook up to internet found no ethernet driver ok I take care of it tomorrow left the unit plugged in and off come home hit the power switch nothing -zero green light yes. Left unplugged over night plugged back in starts up with no trouble. He is no help and I'm lost. Help- what is the problem here??? Plus I want to add a video card like a 8600 gt to play games what should I do????

 

[o1die]

I would unplug and reconnect the main power supply leads going to the motherboard. If you still no post, I would search the bargain hunters sites such as fatwallet or slickdeals for a new ps. I like antec or corsair, which should fit your dell fine.

 

[gasman336]

So this is a power supply issue verus a motherboard issued then? I thought that maybe a thermal switch in the power supply has cut out and once denergized and left off for a while the thermal contact closes and allows the system to come.

 

[o1die]

Not necessarily. You may have a bad motherboard. I simply suggested a starting point for determining which is the problem. A new ps is cheaper than a dell replacement board. The "for sale" sections in the forums have some good deals. Wooferus over at anandtech had some enermax liberty ps for $75. The dell board will be harder to find a deal. Many are btx format. You'll have to remove the dell board and see how it's atatched before ordering a replacement. Intel brand btx boards are available and might work in a dell case. The 965 or p35 chipset is what you want if you decide to upgrade the cpu later on. I found a 965 board for around $65 recently doing a search on yahoo. Most are around $135 or more.

 

[gasman336]

Ok, thank you.

 

[MrLinux]

As it's a Dell, have a good look at the caps on the MoBo, make sure none of them are bloated. From personal (bitter) experience bad caps are still a common problem on Dell PC's.

 

[gasman336]

I'm just a newbie when it comes to this stuff so what would the cap look like on the MoBo?

 

[MrLinux]

The caps are usualy black (some time green) cylinders with a silver top, the top should be flat wih either a 3 of 4 legged cross (if you see what I mean) stamped in them, if the top isn't flat then they are probably blown; if they are all silver then they probably OK (newer type).
Some times they leak onto the MoBo which is easy to spot.

Best bet is to do a Google on "Blown Caps" there's plenty of pictures out there, it used to be a very common problem.

 

[seboj]

I had this problem a couple years back on a family member's retail PC. I'm pretty sure it ended up being the PSU.

Just food for thought. Good luck!

 

[B-Unit]

We have a similar problem with a particular model of HP at work. Its a sign that the PSU is failing. Initially, we have to unplug them, hold the power switch for a few seconds, then reconnect power and things usually take right off. Eventually, ours get so bad, you have to disconnect all peripherals to get them to start up.