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New power supply buzzing - anyone know why?

  • Hey all, I just got a new graphics card (9800gt - the power!!!) and a new 500w power supply to power that power. It can render 21,000 sprites without going below vsync! But the point of this post is that the power supply buzzes when the cpu is under load. :/

    I contacted the manufacturer, they said it should be plenty for my system, but I miss having it ultra-quiet. Anyone know if getting a 700w power supply would stop the buzzing?

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  • That's probably plenty of power for your system. I'm willing to bet it's a defective/shaky fan inside the power supply that's buzzing. When the CPU's under load, more power is drawn and thus the PSU heats up, requiring the fan to spin faster.

  • I don't think it's that - it sounds like electricity. It has a bit of a warble to it, and it keeps alternating between buzzing and not buzzing too quickly. Also, the pitch/hum of the fan stays constant.

  • Hmm. Just out of curiosity, what PSU did you buy?

  • Seasonic SS-500ET 500W. I read that they were good.

  • I could probably vouch for that one. I actually got almost the exact same model last year. Mine is an SS-500ES 500W, though. Works great, haven't had any problems. I'm guessing there's just something defective with yours. You could always RMA your current one and get a replacement.

  • Yeah, based off of hours of googling that's the best option I can find. Still haven't found a reason for it, tho...

  • It might be badly installed to the case, a loose screw could make it buzz. Maybe tightening everything up would fix it. Did you install it yourself?

    If the wattage is sufficient don't be fooled in to thinking higher wattage equals more quality - you should get the lowest wattage that covers your computer, then find a good model. Once I bought an el cheapo PSU and it exploded after six months. 500W should be more than enough for most desktops if you actually calculate the peak power consumption.

  • How many 12v rails does the PSU have? Positive rails only... the negative rail doesn't count. How many amps are on each rail?

    If your PSU has less than 26-28 amps in total across the rails added up, then there is your problem... the GPU is trying to draw more amps than the PSU can supply, and it will cause your PSU to burn out in a short amount of time.

    500W is probably enough, though for a 9800GT I would have gone at least 650W. I have a 1000W Antec in my machine (Quad rail total 100amp) and that's struggling at times with my GTX280's. Watts are really never a good indication of a power supply's true output though... it all comes down to the amps.

    There should be a sticker or printing on the side of the PSU that will tell you how many 12v rails and how many amps per rail.

    *EDIT*

    Nevermind I just googled your PSU... you have two 12v rails with 17a each... it should be fine. Usually the noise you are hearing is caused from overloading the PSU. It could also have a minor fault in it.

    I suggest to phone the store you bought it from, and ask them what they think... I would be inclined to try and get an exchange on it just in case, because if it does have a minor fault and it blows up... it might damage other parts of your computer that will not be covered under the PSU warranty.

    ~Sol

  • It might be badly installed to the case, a loose screw could make it buzz. Maybe tightening everything up would fix it. Did you install it yourself?

    Yes, but at the moment. it's not actually botled to the case, it's sitting outside it, so it's not that unless it's a component inside the psu itself. Also, the problem goes away if I take out the 9800GT - so it seems like it only happens when the PSU is running above a certain power draw.

    If the wattage is sufficient don't be fooled in to thinking higher wattage equals more quality - you should get the lowest wattage that covers your computer, then find a good model. Once I bought an el cheapo PSU and it exploded after six months. 500W should be more than enough for most desktops if you actually calculate the peak power consumption.

    I read on a lot of websites that Seasonic makes quality stuff, so that shouldn't be it - it might just be the one I've got.

    How many 12v rails does the PSU have?

    I have no idea. I can't find it anywhere, and as much as I've tried to understand this whole amps/rails thing, it doesn't make much sense, because it isn't clearly labeled anywhere. Is this it?

    +3.3V24A,+5V24A,+12V117A,

    +12V217A,-12V0.8A,+5VSB2.5A

    I read something about you're supposed to add the amps, so that should be enough, right? The card wants 26amps/400watts. I'm wondering since taking out the 9800GT stops the buzzing if I should get like a 700w one.

    Thanks for the help, everyone!

    Edit after above edit: Yeah, returning it sounds like a good idea. If the replacement still buzzes I'll opt for a higher wattage.

  • Good 500w PSU is more than enough for 9800gt well it aint anything else than good 'ol 8800

    Well I got antec 550w and atm with 1 3870 though I could run two of em in CR... Maybe there's something wrong with it return it to shop and tell em to check it out and give new one.

  • Update - It turns out it wasn't enough. Not because of the wattage - because of the amps. Apparently, adding up the amps across all the 12v rails for the total is not true - each rail is limited to what it says, so even with a 500 watt power supply, the graphics card was still asking for almost double the amps that the power supply was rated for!

    Solution - when shopping for power supplies, make sure to check the amps needed for the card, and get a power supply with ONE 12v rail.

    Here's the reading for anyone who wants to understand everything about power supplies - and really, it's important: http://www.techjamaica.com/forums/showt ... hp?t=52054

  • Adding amps together across rails DOES work, and IS true, if you buy a premium supply, since the rails are BRIDGED.

    Cheap power supplies have separate rails, if they even have multiple rails...

    At least you figured it out. As I keep saying to people, Watts don't mean JACK... it's all about the AMPS!

    ~Sol

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