No video after GPU changes

Hi everyone,

I'm looking for some advice on a problem with my home built pc (I guess it's at 3+ years now). The basic specs are

Gigabyte GA-MA78GM-US2H
AMD Phenom II X4 940
550W OCZ Fatality PSU
(Old GPU) Radeon HD 4670
(New GPU) Radeon HD 6850

+ random bits (1 SATA drive, 1 DVD-ROM) - so the 550W PSU should be capable of handling the hungry 6850.

I've had the PC running problem free for several years with the 4670 installed. Today I uninstalled the 4670 drivers, then physically installed the 6850 (which involved a bit of reshuffling of HDD etc. in the case), but when I turned the system back on my monitor wasn't receiving any signal. I reverted back to the 4670 to check that still worked, and it didn't! I finally tried the onboard video, but that also currently fails to produce any signal. On boot up all fans (including GPU fans) fire up and run well, there are no warning beeps, nothing else to indicate any problem.

It's possible I forgot to reconnect something, but I don't see any loose wires or d/c hardware (and the case is pretty sparse, not much stuff in there to get confused about). I was slightly unsure as to how to power the 6850 directly from the PSU, but that certainly shouldn't make a difference now I'm rolling back to earlier spec to figure out what's wrong, should it??

Any help MUCH appreciated!


6 answers Last reply
More about video changes
  1. with your new 6850 did you plug in the pci-e power plug into it? cause that what i would of guessed why it wasnt working

    and when you tried plug it into the onboard video card did you make sure the video cards werent pluged in? as it wont use the onboard video card if somthing is pluged into the pci-e slot
  2. uninstall drivers,download driver sweeper or driver fusion,go into safe mode clean out old amd drivers,restart download latest drivers
  3. tbh by the sound of his problems that he has, it doesnt sound like he can do that :\
  4. I've often had this happen to me when doing a GPU swap. I'd be willing to bet that a simple BIOS reset will fix the problem. Consult your motherboard manual on how to do this.
  5. Sounds like the psu might have went out when u used the bigger card and now it wont power the mb..Just a guess.
  6. Unseated RAM will prevent a system boot entirely, so yes, that might have been it.
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