Question Increasing bus speed and getting an error


Aug 11, 2019
I recently upgraded my gpu from r7 250 to rx 550. Before I upgraded I had my bus speed increased from 100mhz to 110mhz. (I dont have an unlocked cpu), and everything worked fine.
After I installed a new gpu I put the same settings in bios, i couldn't boot, and i got a 1 long beep and 3 short beeps.(Which means, at least where I read, it is a gpu error).
Any help?
Cpu: athlon x4 840
mb: f2a68hm-h s1
gpu: rx 550
ram: 2x4gb 1600mhz
1ssd and 1 hdd
cheap 550w psu


Think of the pc as a town. Got a bunch of buildings, stores, gyms, parks, townhall etc. Every one of those is interconnected with a road. The pcie buss. Normally roads have speed limits, like 30mph and everybody in town knows them. But in your town, you've changed that to 40mph and that was acceptable.

And then a stranger comes to town, tries running around town doing his normal 30mph and you are surprised when he gets rear-ended as a result.

The Rx series don't like odd buss. They are already pushed and expecting a 100MHz buss and you are changing the speed limits, which changes communication speeds with the gpu internals.

It's also possible it's a bios issue. The Rx series are known for not liking legacy bios at all, some will only work on uefi bios, so look at the card as it might have a tiny physical switch that's used for legacy bios compatibility.
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Jan 24, 2021
Overclocking and a junk power supply, one of my favourite disaster combos that never gets old.

Revert everything back to stock and please refrain from overclocking. If the card uses an aux connector it's possible the PSU is on its last legs already, if it's one of those silver cheapo PSUs remember it's not 550W, more like 300 if you're lucky, the rest goes into the 5V rail that's not being used a lot nowadays, those designs are mostly from early 00's