Question blinking underscore for about half of bootups


Dec 31, 2007
I have a system that is about 11 years old with a Gigabyte GA-K8VT800M motherboard (full system specs below). I am running Linux Mint Ulaya and Windows 10 in a dual-boot configuration. I haven't made any major changes lately.
Recently, about every other time that I restart, the computer drops to a blinking underscore in the upper left. This happens right after the BIOS splash screen and well before the boot loader (GRUB) starts. It tends to happen after a long pause on the BIOS splash screen. It has happened when rebooting from both Linux and Windows. Once it gets to the blinking underscore, it's unresponsive and I have to hit the power button. When I cycle the power button, it usually boots up fine.
I have an external USB drive and I thought maybe that was causing it, but when I tested it by removing the drive it still happened.
The system runs beautifully the rest of the time, so I really want to save it despite its age. Is something gradually dying here? I have tested the hard drives and they report no issues.
Full specs below.
Machine: Type: Desktop System: Gigabyte product: GA-MA790X-UD4P BIOS: Award v: F5
date: 06/03/2009
CPU: Topology: Triple Core model: AMD Phenom II X3 720 bits: 64 type: MCP arch: K10 rev: 2
L2 cache: 1536 KiB
flags: lm nx pae sse sse2 sse3 sse4a svm bogomips: 16872
Speed: 1600 MHz min/max: 800/2800 MHz Core speeds (MHz): 1: 1600 2: 800 3: 1600
Graphics: Device-1: NVIDIA G96C [GeForce 9400 GT] vendor: Micro-Star MSI driver: nvidia
v: 340.108 bus ID: 01:00.0 chip ID: 10de:0641
Display: x11 server: X.Org 1.20.9 driver: nvidia
unloaded: fbdev,modesetting,nouveau,vesa resolution: 1440x900~60Hz
OpenGL: renderer: GeForce 9400 GT/PCIe/SSE2 v: 3.3.0 NVIDIA 340.108 direct render: Yes
Audio: Device-1: AMD SBx00 Azalia vendor: Gigabyte driver: snd_hda_intel v: kernel
bus ID: 00:14.2 chip ID: 1002:4383
Sound Server: ALSA v: k5.4.0-62-generic
Network: Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: Gigabyte
driver: r8169 v: kernel port: ce00 bus ID: 03:00.0 chip ID: 10ec:8168
IF: enp3s0 state: up speed: 100 Mbps duplex: full mac: <filter>
Device-2: Realtek RTL-8100/8101L/8139 PCI Fast Ethernet Adapter driver: 8139too
v: 0.9.28 port: be00 bus ID: 04:06.0 chip ID: 10ec:8139
IF: enp4s6 state: down mac: <filter>
Drives: Local Storage: total: 2.40 TiB used: 683.21 GiB (27.8%)
ID-1: /dev/sda vendor: Seagate model: ST1000DM010-2EP102 size: 931.51 GiB
speed: 3.0 Gb/s serial: <filter>
ID-2: /dev/sdb vendor: Western Digital model: WD6401AALS-00L3B2 size: 596.17 GiB
speed: 3.0 Gb/s serial: <filter>
ID-3: /dev/sdc type: USB vendor: Western Digital model: WD10 01FALS-00J7B1
size: 931.51 GiB serial: <filter>
Partition: ID-1: / size: 68.21 GiB used: 23.70 GiB (34.7%) fs: ext4 dev: /dev/sda7
ID-2: /home size: 165.10 GiB used: 69.58 GiB (42.1%) fs: ext4 dev: /dev/sdb6


That is somewhat characteristic of failing PSUs. They can seem fine but then, under a "perfect storm" of circumstances become unable to provide the necessary wattage/voltages.

Differing problems and increasing numbers of problems are a symptom.

Do you have a multi-meter and know how to use it? Or know someone who does?

Not a full test because the PSU is not under load. However any voltages that are out of spec should be noted.

Look in Windows 10's Reliability History and Event Viewer. If you see many and varying errors then that is also suggestive of a problem PSU.


Dec 31, 2007
Thank you for these tips! It sounds like the PSU failure is extremely common, I had no idea.
I checked the Reliability History and Event Viewer. The former was clean. The latter had many errors but they were all software related (like a program not starting up quickly enough, which I think was my fault for having Steam start on bootup and suck resources when I never use it.)
While I had the case open , I blew out all the fans, including the PSU, with compressed air to get rid of the dust. It has now booted twice in a row without problems. Fingers crossed that this will help.
I do have a multi-meter if it comes to that, but I'd be a little nervous about hurting myself with the voltage. The instructions that you linked are very thorough, though. Thanks again.