# Is my power supply faulty or just insufficient?



## edmunsta (Nov 30, 2007)

Hi all,

Situation:

My computer has been having trouble booting. When this problem occurs, it turns on and the fans spin, but there's no bios beep and no display. If I unplug everything from the PSU except the graphics card and motherboard, the system will boot. If I then turn it off and plug the hard drive molex in, the system won't boot (as above: fans but no beep). This initially seemed pretty simply to me... if it stops booting when you plug one more device in, my PSU must be lacking in wattage to power the system. However, the problem is somewhat intermittent. Through a random combination of turning off and on at the wall, plugging and unplugging the power cable from the psu and turning the computer off and on, I can get the system to boot with the hard drive powered up. The intermittent nature of the problem seems odd to me. 

So to summarise:

When the bare minimum of components are plugged into the PSU, it boots.

As soon as I add one more component (the HDD), it won't boot. 

However, random sequences of powering on and off can sometimes get it to boot WITH the HDD plugged in. Hence why I suspect that PSU might be faulty. 

Does this sound like a faulty PSU or just an insufficient PSU for my system's needs? Specs are as follows:

PSU: Antec EarthWatts 500

Mobo: Asus P5K
CPU: Core 2 Duo E6750
Ram: 2x1GB DDR2 800mhz
GFX: 8800GT (single, not sli)

One sata HDD, one sata DVD RW. 

Should an earthwatts 500 be able to power this setup with no problems? If yes, then would you conclude that I have a faulty specimen?


Thanks in advance


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## emosun (Oct 4, 2006)

Well all I saw at the end was 500w and 8800gt. Which shouldn't be used in the same sentence. That psu is infact to low for that system and you really should have a 650w or more in there. You pick a good quality brand but its still to low.

Now about you boot problem, it almost sounds like upgradeing your psu would fix it, but first try to plug the drive into a different ide or sata port. Also , was the pc working before this happend?


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## edmunsta (Nov 30, 2007)

I'll try plugging it in to another port. Actually I'll also see if it does the same thing with the DVD drive... do HDDs and DVDs consume similar power?

It was a new pc, or at least new mobo/cpu/gfx/ram/psu. From about the second or third day onwards it started having trouble. It just kept getting worse and worse. Previously I could just power on and off a few times and on the third or fourth try it would boot properly. Now a month or so later it takes half an hour of fiddling around and, like i said, seemingly random sequences of on and off at the wall/psu/power button to get it running.


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## emosun (Oct 4, 2006)

Well hdd's and dvd drives do consume power but nowhere near as much as the video card and cpu do. Its starting to sound like a new psu is the answer


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## Tumbleweed36 (May 14, 2005)

I too think you need to invest in a decent Antec Trio 650 or something similar. That video card just pulls too much for this little engine (power supply) to pull it. There are no guarantees that is what it is, but all signs point in that direction.


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## edmunsta (Nov 30, 2007)

Now that I think about it, it could be the graphics card that is drawing too much. The Earthwatts 500 has two 12V rails with 17 amps on each. Apparently the 8800GT cards need 22 amps on the 12V rail. This is getting way out of my level of understanding.


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## emosun (Oct 4, 2006)

Any system with an 8800 should have a 650w or more psu. the antec trio 650 that tumbleweed suggested would be a good choice.


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## cliffnseattle (Mar 3, 2005)

I'm curious if a bigger power supply will fix the problem. I doubt it, since I've been investigating this same problem, and there seems to be hundreds of similar problem reports on the Web for the P5K. On the Asus web site forum, there's been close to 10 reports just since the beginning of this year. And many of them have large power supplies (e.g. 650 or 700 watts), or tried putting in bigger power supplies to no avail.

A number of workarounds have been tried, but none seem to consistently fix the problem. It appears to me to be a design or manufacturing or quality control issue with the MB or BIOS. There may be a common theme (e.g. having both an IDE and SATA HDD versus SATA only), but nobody has definitively identified one.

There's a similar set of symptoms for most of the posts, and none fit with classic "underpowered PS" problems (it seems that the answer to every boot problem is "your PS is underpowered"). One of the commonalities is that booting works fine for a while, then days or weeks later starts to fail (with no POST beep, requiring a random number of power offs or reset button presses). Various "fixes" appear to work (e.g. swapping memory, or clearing CMOS, or a dozen other changes), then after a few days failure to boot happens again. Note that all of the components in the system power up (fans, HDDs, etc), but the MB never gets to the POST beep (i.e. always a dark screen, nothing happening).

Many are speculating a BIOS update will sove the issue - at this point I'm not powering down my computer (and I've disabled S3 sleep mode, since it will not wake up), and will either get a BIOS update that fixes the problem (in a reasonable timeframe), or will finally give up and go back to the guy that built it for me for a swap (or RMA it with Asus, if that's the best option - I've never had to do that before, and don't really want to spend the time rebuilding the computer, since I paid someone to do that for me).

I suggest doing a search in the Asus web site forums for MB P5K for further info - you'll see dozens, with various subtleties involved.

Cliff


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## linderman (May 20, 2005)

regardless how you wish to slice the pie; there is no 500 watt PSU that will run your system reliably for an extended period of time


try your system with a lesser power hungry video card as an aid to the process of elimination


dont forget; the 8800gt is a really hot bugger, if you dont have really good case air flow your PSU is going to be inhaling some very hot intake air :4-thatsba


remember; a PSU gets its "fresh" air from inside the computer case

the hotter a PSU gets, the less capable it becomes

the cd drives and hard drives consume their most power during the initialization phase at start up


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## dai (Jul 2, 2004)

it depends on the quality of the psu's they have been trying,most seem to fall into the trap that a $20-60 700w psu is the same as a $200 one
i am running a p5k e6750 7600gs water cooling 4 h/d's 3dvdrw drives 4g ram
with a silverstone 650w
with no problems at all
when everything is firing up but no screen it is a fair indication that the cause is a crappy or underpowered psu


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## linderman (May 20, 2005)

I have not seen any such issues with the three P5k's I have sold either


two of them are 8800Gt and the other an sli 7950 gtx


all are running great with the thermaltake toughpower 750's power supply units in all three


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## speedster123 (Oct 18, 2006)

i agree
the toughpower 750 and the 650 trio / silverstone can handle quite a steady and pro- longed load.


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