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Concupiscence
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Tutti Frutti Display Woes

Mon Jul 02, 2018 9:23 am

So I'm probably dealing with a dead motherboard - specifically, a Biostar H77MU3 - but I've never seen one fail this way before, and I've been building PCs since 1996. The story follows.

I put together a little box to use as a workstation / computational node for working with seismic data, separate from my main rig. It sports an i5 3570K, 16 gigs of DDR3-1600, and the aforementioned motherboard, along with a Rosewill PCIe wireless NIC, a plain vanilla HIS Radeon 7850, and a brand new SeaSonic 620W power supply. I tried to boot a BunsenLabs flash drive, which complained it couldn't set a valid video mode. I yanked the Radeon and used the IGP. It still bitched about an invalid video mode, so I switched to a Xubuntu flash drive and that worked without a hitch. Swapped the Radeon back in, had no issues, updated the system... and suddenly the wireless card didn't work any more. Tried disabling it to force a firmware reload, rebooted, tried to re-enable, and the Additional Drivers dialog insisted that the hardware wasn't working. Then I shut it down to take the Radeon out... and it all went to hell. Tutti Frutti hell.

Image

Forgive the poor focus of the image, but it flashes this gibberish for one second, turns the signal off, and repeats in an endless loop. My iPhone had trouble keeping up. I don't have a buzzer or PC speaker installed, but removing the RAM results in a black screen, so something during POST is failing between initial RAM identification and display init. Because no good deed goes unpunished, I took it all apart to make sure nothing was shorting against the motherboard, put it back together... and now it doesn't power on at all. I suspect the latter may have something to do with my using a magnetic screwdriver to take out the screws - forgive me, it was late and I was tired - so maybe, with fingers crossed, it'll at least power on after I put my kids to bed tonight.

I'm kind of at a loss. Any advice is greatly appreciated.
Media: Core i9 7940x, 32 gigs RAM, GTX Titan Xm, Win10 Pro
Science: Ryzen 7 1700, 16 gigs RAM, RX Vega 56, Xubuntu 18.04
Server: Xeon E5-4640, 32 gigs ECC RAM, FirePro V8800, Win10 Pro

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Re: Tutti Frutti Display Woes

Mon Jul 02, 2018 11:42 am

Concupiscence wrote:
So I'm probably dealing with a dead motherboard...I took it all apart to make sure nothing was shorting against the motherboard, put it back together... and now it doesn't power on at all. I suspect the latter may have something to do with my using a magnetic screwdriver to take out the screws

Unlikely. Your own diagnosis of a dying motherboard is probably correct, and moving things around finished it off. Last chance: pull the board completely out of the system and disconnect everything, pull the backup battery, and let it sit overnight. Then replace the battery and set up just the motherboard, CPU, and a minimum RAM configuration on a clean, non-conductive surface. Try to POST and access the BIOS/UEFI with nothing but the iGPU and a known-working keyboard. If that doesn't work then you've pretty much confirmed a dead motherboard.
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Re: Tutti Frutti Display Woes

Mon Jul 02, 2018 12:32 pm

There is nothing in a modern PC which would be adversely affected by the presence of a magnetic tip screwdriver. Even a mechanical HDD would not be damaged, unless you use the handle end of the screwdriver as a blunt instrument to pound on the drive, or take the lid of the drive off and drag the screwdriver tip across the platters.

You're just going to need to go by process of elimination to narrow things down. I'd say your potential culprits (in decreasing order of likelihood) are motherboard, RAM, CPU, PSU.

The display that flashes up is almost certainly the GPU attempting to display the contents of an uninitialized frame buffer.
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Concupiscence
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Re: Tutti Frutti Display Woes

Mon Jul 02, 2018 12:37 pm

just brew it! wrote:
There is nothing in a modern PC which would be adversely affected by the presence of a magnetic tip screwdriver. Even a mechanical HDD would not be damaged, unless you use the handle end of the screwdriver as a blunt instrument to pound on the drive, or take the lid of the drive off and drag the screwdriver tip across the platters.

You're just going to need to go by process of elimination to narrow things down. I'd say your potential culprits (in decreasing order of likelihood) are motherboard, RAM, CPU, PSU.

The display that flashes up is almost certainly the GPU attempting to display the contents of an uninitialized frame buffer.


My main suspects at this point are the motherboard and CPU. The RAM was working for the friend who sold me this kit last week without issue and passed a full diagnostic, and thunking in each DIMM in succession yielded the same behavior. The power supply's also brand new and made by SeaSonic, and at a 620 watt capacity should be wildly overqualified for a stock 3570K and a single SSD. I can figure out a way to test it, but bad power supplies tend to be... twitchier than this. The CPU's probably alright too... and given that the BunsenLabs kernel complained it couldn't initialize the display on both the Radeon and the IGP (the latter to the point that it basically thumped me to a kernel debug prompt), I suspect the motherboard's botching something in the way it initializes video. What fun. More testing to come tonight.
Media: Core i9 7940x, 32 gigs RAM, GTX Titan Xm, Win10 Pro
Science: Ryzen 7 1700, 16 gigs RAM, RX Vega 56, Xubuntu 18.04
Server: Xeon E5-4640, 32 gigs ECC RAM, FirePro V8800, Win10 Pro

Read my words at https://www.wallabyjones.com/

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