Dell Inspiron 530

Hi Folks,
My Dell desktop has recently developed a strange fault and I would appreciate some advice, please.
After the computer has been left overnight with the power switched off at the wall socket, pressing the start button ( will flash orange) and only allow the two internal fans to spin up for approx. 1 second then stop. If the start button is held in, the fan start/stop process repeats every 1 second or so but the computer never fires up. However if I leave the mains power connected to the computer for 10 minutes or so the computer will fire up (light turns blue) and all is OK. If I put the computer into sleep mode it will also wake up, light turns blue and all is OK.
I've replaced the 3v battery, tried removing the RAM and the hard drive but nothing works. I suspect the PSU but can't be sure. Also the are a number of "compatible" PSU's on the market but most seem to be 300w where as mine is rated at 350w.
64 bit Quad CPU Q6600@2.4GHz with 4GB of RAM
Your comments would be appreciated.
Regards
Geoff

 

That is what it sounds like.

Note when you simply shutdown the computer and don't unplug it from the wall (or in your case, flip the wall socket switch), that really puts the computer into standby mode. The power supply is still outputting +5Vsb standby power to many points on the motherboard to keep various features alive. These include the ability to wake the computer by wiggling the mouse or pressing a keyboard key, or even using the computer's front panel power button.

Even though this +5Vsb is a very low power output, I suspect this is just enough to keep a failing component warm. Remembering that matter expands and contracts as it warms and cools, my guess is there is a failing component in the PSU that has a tiny microfracture that "opens" when cool and expands shut when warm to complete the circuit. I also suspect it will only get worse and soon it will take 20 minutes, and then longer to warm up enough, then no warm up time will work.

Sadly, it is very difficult to conclusively test power supplies. It takes a qualified technician with an oscilloscope or a power supply analyzer, and the supply must be tested under a variety of expected loads. And it is even more difficult when the problem appears to be intermittent. So even for pros, often the best way to test is to swap in a known good spare.

Unfortunately, Dell is notorious for using proprietary power supplies in their computers. Since American homes don't have such wall outlet switches, I am guessing you are in the UK? I don't know about sourcing replacement supplies there. Newegg here in the US has several 350 and even 400W supplies. When I looked at Newegg UK, I found a 420W supply, but when I clicked on it, I got a page not found error. While a 300W supply would probably support your hardware, I personally would prefer to replace the supply with the same size or something bigger - not smaller.

 

Many thanks for you advice.
In addition to the symptoms above, over the past few days the time I needed to leave the PC plugged into the power increased and, if I placed the PC in sleep mode via the windows button the PC would wake up and run fine apart from now the blue power button would blink every 1 sec. or so - very strange!
However, all the above symptoms turned out to be the power supply. I managed to locate a suitable reconditioned 350W one and now the PC works fine.
I thought I would add this final post in an effort to help anyone else who experienced the same symptoms.
Regards
Geoff.

 

Thanks for the feedback.