Can I safely use a 300W power supply to replace a 250W bad unit in my eMachines

I have a eMachines W2040 which I believe has a bad power supply because nothing happens at all when you try to turn it on. I took a power supply out of an older unit and it at least got lights going and all, but did not boot up. I'm assuming because the wattage on that power supply was less than my 250W. So, without upgrading anything else, can I successfully replace my 250W power supply with a 300W and not risk frying anything with the extra wattage? I am capable of changing out the pieces, I'm just not that technically educated in the inner workings and power stuff about computers. I would be replacing a Bestec ATX 250W 12E with a Bestec ATX 300W 12E.
Any input is greatly appreciated!
8 answers Last reply
More about safely 300w power supply replace 250w unit emachines
  1. Should be fine. You could stick a 500W in there and if the machine only drawls 100w it will only draw 100w. The larger power supply won't force more power into the system, only allow the system to draw more power then the 250w IF the system requires more power.

    Basically upping the power supply doesn't increase the watts going into the system, it only allows the system to drawl more watts if it needs to.
  2. Thanks, I think I'll go ahead and order one and give it a go. I was thinking that was the case, but I am not real fluent in this type of thing and don't want to screw up by assuming. :)
  3. ^5 +1 what runningbot said. However, I am not so sure about purchasing another Bestec power supply. They never had a reputation for high quality power supplies. In fact, do not be surprised to find out the psu damaged your motherboard.

    Here is a link to an excellent technical review over at

    Corsair and Seasonic are two brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty. Lately we've been seeing a few other brands offering some high quality units. One example would be the newer Antec power supplies.
  4. I own all Antec PSUs and have been very pleased. I've been running Antec since 1998 and never had a problem.
  5. Thanks JohnnyLucky. Good call, I think. Maybe what happened next means my mobo is bad now?

    I replaced the power supply with a spare working one a friend had. So...when I plugged it in (keeping drives unplugged per some advice I read online), the fan started. Then, I started to plug in drives and when I hit the power button on the front, the cd drive light came on and it sounded like it was checking for a disk. I'm not sure the floppy made any noise and the hard drive made a little noise like it was trying to do something and the hard drive light blinked a few times. The fan kept running, but no beeps and nothing to the monitor. So I unplugged everything I could, checked behind it for dust interference and checked all the capacitors and such. Everything looks intact, attached and without any buldges or anything that looked 'not right'. Through process of elimination by plugging things back in one at a time and testing, still same results of no beeps and nothing to the monitor but the new thing is that the fan only comes on when I push the power switch on the front instead of coming on when the CPU is plugged in. Aargh!
    My biggest concern is keeping what is on my hard drive. I'm on a rather tight budget and my laptop is down also (tries to turn on but never boots). I'm starting to think my computers are conspiring against me! Should I just get a used CPU that is compatible with my hard drive or try fixing the emachines one? Or, is there any way that my emachines hard drive can be connected to my Dell laptop? I'm thinking not, but hopeful that there is a reasonably priced option out there for my rather limited budget. I need to get back on my computer to get back into some home business stuff I do on the side.

    Thanks so much to you and runningbot for your input. If you have any more to add, please do. I greatly appreciate all the help and advice I can get! :)
  6. was the original psu a bestec atx-xxx-12e? (xxx=wattage).
    if so, then it fried your mobo. while the 12z series is fine, the 12e series has a critical design flaw where it spikes very high on the 5vsb...
  7. Yeah, it was the atx-250-12e. :( And the one I have in it now is an atx-300-12e-d. Should I be concerned with this one too? Or could I be so lucky that the 'd' means they have identified the problem and fixed it, thus giving it a slightly different identification? I'm guessing my luck isn't that good, but if you never hope for may never get it.
  8. i dont think i would use any 12e psu. they are konw to fry mobos. i saw it at and i have experienced it twice. (once a neighbor, once a family member)...
Ask a new question

Read More

Power Supplies eMachines Components Product