Cannot get computer to boot when new graphics cards are installed

[FallingPiano]

I've been struggling with this problem for a few days now. Installing a pair of R9 270x into a crossfire compatible mobo with an 850W power supply. The computer boots fine when the monitor is hooked up to the integrated graphics and runs Windows well, but as soon as the graphics cards are seated and powered the computer won't boot. No bios beeps, no display on the monitor, nothing else. I've checked to make sure that PCI graphics are enabled in the bios. I've uninstalled all other drivers using DDU. Any suggestions?

 

[FallingPiano]

Also, the fans on the cards spin up when they are powered from the molex cables from the PSU.

 

[Cromisa]

I haven't had an issue with 2 cards like you are, but single cards have done this to me in the past, typically a BIOS flash has done the trick, mainly because the cards are newer than the MB BIOS is.

Not sure if this will help you at all, but it might be worth a shot.

Can you try just a single card?

 

[Cromisa]

Oh wait, sorry just re-read your post, have you changed the Primary display in the BIOS to PCI-E?
Not sure if your statement about PCI being enabled is the same thing...because you can enabled them but not have them as primary display.

If the onboard is still primary, that would explain why there are no beeps, because it's booting fine.

 

[FallingPiano]

Yeah I have actually been trying just a single card to see if I can get anything to boot, good suggestion though.

The cards are definitely newer than the mobo. The mobo is at least 2-3 years old, a GA-Z77-D3H. Would flashing a newer bios affect the cards at all? Sorry, never had to deal with installation into an older mobo before (all other builds have been with new components) and never really had to mess around with flashing an updated bios.

EDIT: and yes I have changed the primary to PCI. The mobo DOES beep when it boots into windows correctly with integrated graphics. It isn't beeping with the cards connected currently.

 

[Cromisa]

Right, so then I would say give the flashing a try. You just need a usb stick pretty much, then go onto your MB's website, there should be a location to download the latest BIOS - they should also have instructions on how to unpack the files.

Then it's just a re-boot into BIOS, plug in the USB and flash it.

Only other thing I could think to check is to disable on board video, boot up the PC without a card in the PCI-E slot - this should give a few beeps etc - which means at least you know that part of the MB is working. Then plug in a single card, if you still get no beeps, then flash away!

 

[FallingPiano]

Thanks! Flashing the newest BIOS did the trick and fixed all the issues I was having.