No POST boot with HD Radeon 5850

Hi All,

Here is a tricky one that I would appreciate any help with:


AMD Phenom II 965
Gigabyte GA-880GA-UD3H
Maxtor SATA2 7200 Hard disk
Radeon HD 5850 1GB
850W PSU


I have a 1x6 pin power connector (direct to PSU), and another 6 pin (5 pin only) x 2 MOLEX converter that connect the GPU to the PSU and obviously the PCI-e. Everything was running smoothly until I removed the CMOS battery (long story), and since then this GPU has been having issues, don't think there is any relation to the CMOS at this point however hard to believe in 'just coincidence'.

So the situation now is when the GPU has both power cables in, Desktop will not POST. No BIOS, no screens, no beeps, nothing. Lights are on, CD turns, Hard drive shows activity, fans go full bore, but thats it. Even GPU fan going.

If I remove one of the connectors (either) or both and leave the GPU in the PCIe slot, the computer will boot and everything is fine. Obviously 5850 isn't running due to lack of power (i assume), but the computer boots up and the internal VGA allows me to check BIOS and boot up windows. I have swapped the GPU with an older card and it works fine. I can use DVI on the card, and the connectors work (well can only use one 6 pin at a time in this card, but both work individually fine, which leads to me the connectors are not the problem.)

Now I have deducted that the PSU should be more than adequate to take the load, so my logic would point to something deep in the card and is busted.

Wondering your thoughts? Would there be a setting in BIOS that my have been reset when the CMOS battery was taken out, and there fore the card does not receive adequate V?

I'll be purchasing a new 6970 tomorrow and whatever is needed to install it, however I'll check this tomorrow morning and see if anyone has any ideas before launching into it.

Cheers for any feedback.

7 answers Last reply
More about post boot radeon 5850
  1. Wow your 850W PSU doesnt have 2 x PCI-E 6 pins? What make is it?

    I'd recommend booting into BIOS and disabling on board video so the system boots with the HD5850.
  2. Thanks for the reply,

    Now that you mention it, it doesn't have a brand. Just a generic 850W ATX power supply. Maybe something to look into.

    Unfortunately tried that, and the PCIe is set as the initial check anyway. But the issue also is that the computer is not even booting past POST when the 5850 is plugged in fully. It was all working fine until that damn battery...

  3. I wouldn't trust that PSU at all, if it doesnt have 2 native PCI-E 6 pins then that would suggest to me that the PSU wasn't designed to power a card that requires 2 6 pins.

    Though the PSU may not be the problem. If you boot into windows with the onboard video can you see the HD5850 in the device manager?
  4. Hmm, very valid point actually, but don't the cards get sent with the 6-pin->molex converters on them, so I thought it was a normal thing :S.

    Yeah tried it with one 6-pin in there and no pins, still nothing unfortunately. 850W should be enough though, do you agree?
  5. Well you would have thought so, depends how many amps/watts are on the +12V rail(s)

    No point trying the card with anything less than both 6 pins connected...

    Did you check device manager?
  6. True,

    I did check it, but it didn't show up. I just don't know why the computer would boot with only one 6-pin in the card, instead of the 2.

    I guess ill be getting a new PSU as well to be sure.

    Thanks for your input.
  7. If you can, test the card in another PC with a different PSU

    You could also try the card in another motherboard slot, and with another molex to 6 pin adapter.
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