Question Gigabyte z390m and Sapphire Pulse RX580 sometimes starts, sometimes doesn't, sometimes draws screen slowly

Kaitain Jones

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May 18, 2015
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EDIT: I've realized that sometimes the PC doesn't really start at all. I noticed that in the cases where I don't see anything on the monitor through the graphics card on boot, I also don't see any lights come on on the keyboard, whereas I always do during a successful boot with output through the mobo HDMI, and in the cases where the PC does start with output through the GPU, both at normal speed and slowly.

So the PC feels at the moment like a car that sometimes starts and sometimes doesn't. Right now it seems to be random whether or not it will start successfully; if it fails, I force power shutdown and try again. Within three or four tries it seems to start. I have no idea why. Could it be that the PSU sometimes copes with the initial surge to all components and sometimes doesn't? The PSU was rated for 700W but maybe it's just not up to the job.

----- Original post -----

I've built a couple of PCs before but have never encountered what I'm seeing at the moment.

I decided to try building a Hackintosh as a tech project, so bought a Gigabyte z390m Gaming, Intel i7-9700k and Sapphire Pulse RX580. This is my first experience using a UEFI board, so maybe (?) this is part of why what I'm seeing is confusing me.

In short, at times I'll get an output from the graphics card, at other times I'll only get an output from the mobo's HDMI, and in the worst case scenario I won't get any output at all until I've disconnected power from the graphics card and plugged into the mobo HDMI.

In addition, sometimes the BIOS screen (yeah, I know it's not really traditional BIOS) will draw its splash screen very slowly (around 3 secs to render the screen, slowly from top to bottom) and all subsequent screens will be similarly slow until such time as I get into an OS on the machine, at which point it seems to be okay. This only happens when output is coming from the graphics card, not from the mobo HDMI.

And sometimes upon booting I will get a signal to the monitor, but it will just be a black screen: no splash screen; nothing.

I flash-updated the board's BIOS to be the latest stable. But I still get the issue.
I replaced the RX580, fearing that it was faulty. But I still get the issue.
 
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Kaitain Jones

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May 18, 2015
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make and model of the psu?
FSP Group 700W ATX

Slightly oddball choice, but it's to fit inside the long-but-not-tall PSU bay of an old PowerMac G5 case. I ended up powering the GPU using an adapter cable - 8 pin PCIe to 2 x Molex.

I haven't noticed any issues with the GPU (or PSU) during normal operations. Do you think it might have erratic behavior during the initial moments of powering up or something?
 

Kaitain Jones

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May 18, 2015
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Following up on this:
The mobo was faulty. I replaced it and everything now functions properly. Curious that it appeared to manifest in this very specific, odd way.
 

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