When I switch my newly built PC on, the fans start up, but I get nothing on the monitor, and the POST display on the motherboard runs quickly through various codes and then stops at code 18, which does not appear in the manual (the list there seems identical to this one).

This lasts about 10 seconds, after which the machine shuts down. After a pause (also about 10 seconds) it starts up again, and this repeats until I cut the power. Interestingly, when I push the reset button, it stops at POST code 16 (which is also not listed in the manual). Does anyone have information about the meaning of those codes?

  • Motherboard: ASRock P55 Pro
  • CPU: Intel Core i3 530
  • Graphics Card: Sapphire HHD 5750

Does anyone have experience with that Motherboard/CPU combination? It says on the packaging and in the manual that it's only compatible with Core i5 and i7 (no mention of i3), but on the maker's product page, the i3 is listed as compatible as well.

2 Answers 2


If the i3 is not listed in the documentation that came with your board, but is listed on the manufacturer's website, there's a very likely chance that support for the processor was added in a recent version of the BIOS. Your computer may be new, but it really depends on how long that specific motherboard was sitting on the shelf before it was selected. If you happen to have a working processor that can be spared temporarily, you can check and/or update the BIOS.

I'm currently digging around the web to see if I can find either of those error codes.

  • Thanks! I've found a sticker on the BIOS chip that says "P55 Pro P2.20-15A", and according to the CPU Support List, BIOS version P2.20 should support the CPU. I wish I had another CPU to try, but I don't. I'd actually be willing to buy an i5 instead, but what if that doesn't help either? Damn, why can't one update the BIOS without a CPU? Jun 4, 2010 at 23:35
  • @Michael Borgwardt Because how does one run update code without the CPU? :P Also, having no luck on finding those error codes, or any documentation about the "Dr. Debug" feature at all. :( Jun 4, 2010 at 23:48
  • Me neither. That's idiotic, given that it's the whole point of that feature. If there had been a complete list out there, if would have saved me hours of frustration. Jun 5, 2010 at 9:33

OK, looks like the CPU thing was a red herring. The real problem was RAM. Apparently one of the two 2GB modules I ordered is completely broken. If I remove it, the machine boots just fine, no matter what socket the other module is in. Stupid thing is, I'll probably have to send them both back, as I bought them as a set.

BTW, I found a very good guide for troubleshooting custom-built PCs at Tom's Hardware.

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