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Will Graphics Card Run If PSU Provides Below Minimum Power?

I just bought a new sapphire hd 3850 ati (agp) graphics card to replace my onboard video. I installed it and everything seems to be fitted properly. However when I start my computer nothing shows on the monitor and the indicator light shows orange. No beeps either.

I just found out that the card requires 450W. My psu only does 350W. Will that prevent the card from working?

I have a few other questions to determine the problem:

1) Is a graphics card fan supposed to turn on as soon as you start your computer?

2) What does it mean if the fan runs (constantly, not flickers) when the cord to the psu is disconnected but the computer is on?

3) When you install a new modern graphics card, do you have to mess around with BIOS settings or does the card drivers reconfigure them automatically?
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  1. Yes, you need a better PSU for that card. If it was a quality brand PSU then it might have worked but apparently that isn't the case.
    A new video card should be recognized and used automatically.
    You may want to consider an HD4650. Not quite as good as an HD3850 but it uses a lot less power and will probably be fine for your PSU.
  2. well, that card should work fin on a 450 watt PSU

    1.yes

    2.it is taking power through your mobo

    3.not usually
  3. Ok, thanks so much for your replies I was really confused (especially when the fan was running while disconnected :sweat: ).

    One more question, can anyone recommend a 450W psu that's fairly cheap but gets the job done?

    Really, I'm just running games like Atlantica and WWW but I want the graphics to be as good as they can be.
  4. Best answer
  5. Best answer selected by Blinxer.
  6. Upendra09 said:


    Careful! Some versions of the 3850 take a 6-pin power connector, but others need an 8-pin connector. I believe most of the AGP 3850s were 8-pin, because AGP slots deliver less power directly from the motherboard than a PCIe slot. (Similarly, a lot of AGP 4650s need a Molex or a 6-pin connector, while the PCIe versions need no external power connector at all.)

    So, double-check your card and make sure you get a power supply with either an 8-pin or at least a 6+2 connection if that's the case.

    Also, to answer the OP's third question -- if you have onboard video, you will often have to disable that in the BIOS when you install a new card. Some boards will autodetect, some won't. But on older motherboards (which is what I'm assuming this is), you usually have to do it yourself.
  7. If BIOS doesn't come up its very possible that it needs more power. however, its possible that it could still work. You could try taking it out, going into BIOS, changing the Display Device to AGP vs onboard, save, shutdown. Put the card in and boot again, see what happens.
  8. Im running a radeon 3850 on a 200w PSU :s seems ok but not sure how long it will last...
    does anyone here know much about PSUs, my pc (shuttle Sv22) comes with an unusually shaped psu, its a lot thinner than most (150x82x43) and as its only 200w im having problems finding an upgrade. the s/n is hipro hp-u200ef3...
    any ideas? thanks
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