Question RX580 vga post fail on b450 tomahawk

Sep 18, 2019
Just built this thing (first time in like 20 years so...)

ryzen 5 2600 on a b450 motherboard (so no onboard graphics), RX 580 8gb pulse graphics, corsair 550w psu (details below);

Had all running yesterday. Spent the evening installing, downloading and updating, restarting.. computer slept last night, woke it and then another restart (something crashed when I tried to run a MATLAB installer!?) - then a blank display. POST fails on VGA (mb VGA debug LED is on).

The monitor is getting a blank signal (it comes on with computer power on, but blank screen).

(One hint maybe, it took me a while to figure out that I couldn't get any display with hdmi, after I first assembled it, it posted but without display and waited for input.. had to scrounge up a dvi monitor and cable - thought I'd figure out hdmi later - is it always the case that hdmi out has to be set up with GPU drivers installed? or should they have worked from the outset)

tldr; post fails on vga, no display - computer worked initially

what could it be? what should I try?
Computer Type: custom desktop
GPU: Sapphire Radeon RX 580 8 GB PULSE
CPU: AMD Ryzen 5 2600 3.4 GHz 6-Core
Motherboard: MSI B450 TOMAHAWK ATX AM4
RAM: Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3000 Memory
PSU: Corsair CXM 550 W 80+
Operating System & Version: Windows 10
GPU Drivers: probably 19.9


If there are any steps listed here that you have not already done, it would be advisable to do so if for no other reason than to be able to say you've already done it and eliminate that possibility.


make sure your motherboard has the MOST recent BIOS version installed. If it does not, then update. This solves a high number of issues even in cases where the release that is newer than yours makes no mention of improving graphics card or other hardware compatibility. They do not list every change they have made when they post a new BIOS release.


go to the product page for your motherboard on the manufacturer website. Download and install the latest driver versions for the audio and network adapter (Ethernet/LAN) chipsets. Do not skip installing a newer driver just because you think it is not relevant to the problem you are having. The drivers for one device can often affect ALL other devices and a questionable driver release can cause instability in the OS itself. They don't release new drivers just for fun. If there is a new driver release for a component, there is a good reason for it. The same goes for BIOS updates.

Next, go to the AMD website and download/install the latest B450 chipset drivers.

IF you have other hardware installed or attached to the system that are not a part of the systems covered by the motherboard drivers, then go to the support page for THAT component and check to see if there are newer drivers available for that as well. If there are, install them.


Make sure your memory is running at the correct advertised speed in the BIOS. This may require that you set the memory to run at the XMP profile settings. Also, make sure you have the memory installed in the correct slots and that they are running in dual channel which you can check by installing CPU-Z and checking the Memory and SPD tabs. For all modern motherboards that are dual channel memory architectures, from the last ten years at least, if you have two sticks installed they should be in the A2 (Called DDR4_1 on some boards) or B2 (Called DDR4_2 on some boards) which are ALWAYS the SECOND and FOURTH slots over from the CPU socket, counting TOWARDS the edge of the motherboard EXCEPT on boards that only have two memory slots total. In that case, if you have two modules it's not rocket science, but if you have only one, then install it in the A1 or DDR4_1 slot.


Make sure the problem is not just a bad cable or the wrong cable IF this is a display issue. If it is NOT related to a lack of display signal, then skip to the next step.

This happens a lot. Try a different cable or a different TYPE of cable. Sometimes there can be issues with the monitor or card not supporting a specific specification such as HDMI 1.4 vs HDMI 2.0, or even an HDMI output stops working but the Displayport or DVI output still works fine on the graphics card. Always worth checking the cable and trying other cables because cables get run over, bent, bent pins or simply were cheap quality to begin with and something as simple as trying a different cable or different monitor might be all that is required to solve your issue.

The last thing we want to look at,

for now anyhow, is the graphics card drivers. Regardless of whether you "already installed the newest drivers" for your graphics card or not, it is OFTEN a good idea to do a CLEAN install of the graphics card drivers. Just installing over the old drivers OR trying to use what Nvidia and AMD consider a clean install is not good enough and does not usually give the same result as using the Display Driver Uninstaller utility. This has a very high success rate and is always worth a shot.

If you have had both Nvidia and AMD cards installed at any point on that operating system then you will want to run the DDU twice. Once for the old card drivers (ie, Nvidia or AMD) and again for the currently installed graphics card drivers (ie, AMD or Nvidia). So if you had an Nvidia card at some point in the past, run it first for Nvidia and then after that is complete, run it again for AMD if you currently have an AMD card installed.




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