PC Power Supply troubleshooting

April 4, 2004 1:54 AM

I think my PC's power supply might be acting up. What are your thoughts?

Firstly, if I ever have to unplug it from the wall and then plug it back in, it won't start until 15-30 minutes later (there is an green LED light on the motherboard which doesn't light up until it's ready to go); but at the same time, my monitor (which is plugged in to the power plug coming out of the PSU) is able to turn on as necessary during this time.

Secondly, when ever I play an MP3, playback is stuttered and scratchy (yeah, kind of vague, but it's the best way I can describe it). I've had the case open during the weekend swapping drives in and out, but playback suffers no matter whether I play said MP3 from either HDD (this behaviour just started today).

I think the restarting problem probably coincided with my installation of a new, suped-up video card which might be sucking down more juice than its predecessor, and when I was playing around with drives in the weekend I actually had to unplug one of my CD drives just to start it up (otherwise it turned on for a split second before powering down, before even getting to the power-on test).

I'm thinking my 300 watt supply is either giving up the ghost or just doesn't have enough "oomph". Anybody else care to share their opinion?

posted by John Shaft to computers & internet (13 comments total)

My power supply corrupted 3 of my 4 hard drives when the 12v rail dropped by 3 volts. It had the same warning signs as yours did. I learned the hard way: 65 movies, 7 thousand songs. Do yourself a favor and buy a new power supply, it wont get any better.
posted by Keyser Soze at 3:42 AM on April 4, 2004

while power supplies fail much more often than mother boards, i had vaguely similar problems (starting required pressing the button on the case for a long time) from a bad (i think cracked somewhere) mobo (i changed power supplies and it didn't help).

the other thing to check (prolly obvious) is fans as they fail regularly (but unlikely to give the problems you see).
posted by andrew cooke at 5:03 AM on April 4, 2004

I'd buy a new power supply and check it out.
posted by cheaily at 6:46 AM on April 4, 2004

On a related not, what does it mean to have the 12V rail sticking at 1.65 in a monitoring application? Is this an indication that the power supply is bad, or that I've just used up all of the 12V juice available to me? Is this a portent of bad things to come?
posted by pissfactory at 7:49 AM on April 4, 2004

I heartily second just getting a new power supply. I had been using the same 250w supply that had come with my case for years as I added extra hard drives, multiple cd/dvd drives...after a while, my computer became REAL wonky. sometimes I would turn my computer on and the hard drives wouldn't start spinning until 15 minutes or so passed and even then, everything would move along very sluggishly. then one day I picked up a 550w supply off of ebay (I think it was only like $20) and it was like getting a whole new PC.
posted by mcsweetie at 7:54 AM on April 4, 2004

pissfactory - i would be surprised if your computer was still working if it's really 1.65V when it's supposed to be 12. maybe the software is faulty?
posted by andrew cooke at 8:19 AM on April 4, 2004

When you say still working? You mean working at all at that voltage to begin with or hosed beyond belief because I let it work at that voltage?

Bad monitoring software? That's what I was thinking (hoping). I was hoping that it would just act erratic being under voltage and give itself away, rather than hurting anything as it would if it were over voltage. I'm just going to let it ride and see what happens- it is a work computer built for my 2nd job, so I really don't want to dig up a volt meter and spend any more time on it.

The chip is a P4 2.8 running at 45C where my P4 2.6 at home (overclocked 20%) runs at 29C. I think 45C is still a fine temp for the P4, no?

I love AxMe. Is is OK to piggy back on other people's questions like this, etiquette-wise?
posted by pissfactory at 8:45 AM on April 4, 2004

Not all power supplies were created equal. 300W is often considered the bare minimum to safely operate a modern Intel or AMD computer with a minimum number of peripherals. I recently upgraded from an old PC Power and Cooling Silencer to a Seasonic Super Tornado. The Seasonic power supply is one of the most thoughtfully developed and packaged devices I've bought in more than two decades of computing. The PC Power and Cooling wasn't in any way bad, but the unit just couldn't take being plugged in to the Florida grid and was over three years old.

In a worse case scenario, go to Best Buy and pick yourself up one of these. Try it in your machine, see if it works. If you don't like the power supply or it doesn't fix the symptoms, Best Buy has a no questions asked 30 day return policy.
posted by sequential at 10:34 AM on April 4, 2004

You can use this handy tool to find how much wattage your system might use. It seems a bit out of date, but it will give you a general estimate.
posted by falconred at 12:04 PM on April 4, 2004

Im too lazy to look for a review, but in Hardocp and Tomshardware they give the Antec Truepower series very high recommendations, because of its reliability and high output. If its 100watts more than you need, thats 100watts guaranteeing your machine isnt under fed.

Also, the 12v rail displaying at 1.65 has to be your Vcore instead. Vcore= CPU Core voltage. If your 12v was honestly at 1.65 your computer would not even turn on.
posted by Keyser Soze at 4:21 PM on April 4, 2004

Keyzer, I've owned the Antec. The primary reason I chose to replace it was noise. The Antec has two fans and is noticeably louder than the Seasonic. Considering I have 4 other 80 mm fans in the case, this was an issue for me. The Seasonic is also the most efficient power supply I have ever used.

Here are two reviews of Seasonic PSUs.

Here are two reviews of Antec PSUs.

(The last link compares 15 different power supplies. Lots of juicy details.)
posted by sequential at 4:59 PM on April 4, 2004

Thanks for your help, all. I've been looking at new power supplies from various online outlets, and I notice some have fans on the top (or bottom) as well as the back; this doesn't strike me as particularly useful. Either you're blowing air into the top of the case which won't be ventilated, or into the rest of the case, which doesn't need anymore help keeping warm, thankyouverymuchforasking. Or am I misinterpreting these photos? (e.g. this one).
posted by John Shaft at 9:33 PM on April 4, 2004

John, I believe the fans on the top are intake fans and the fans on the back are for moving air away from the power supply. The basic assumption is that the ambient case temperature is going to be lower than the power supply temperature, so why not actively force air through the PSU?

The Seasonic has a 120 mm fan on the top. This struck me as odd because it has no fan on the back. However, after careful inspection, the 120mm fan moves more than enough air over the power supply to keep it nice and cool.

Two fan units are typically louder, but you can mod them with very little knowledge of power supply units. All you're really doing is replacing or modifying the fan. (Just make sure you unplug it before removing the cover.)
posted by sequential at 10:08 PM on April 4, 2004