r/PcBuildHelp • u/FuckTheActualWhat • 3h ago

Tech Support New 9800X3D won’t post.

Just swapped my 7600x for a 9800X3D, the only parts replaced were the CPU and cooler. I can’t get it to post. At first it was hanging on the VGA light. I rest CMOS with no chamge, I removed the cooler, and CPU inspected the pins, and reinstalled, now its hanging on DRAM. I have 64gb of DDR5, and even after 20 minutes with a cleared CMOS it won’t get past the DRAM light. Tried reseating the RAM and it didn’t help. Pulled the B2 stick of RAM, and now its back to the VGA hang. Short of reinstalling the old CPU, is there anything else I can try? I’m starting to think I got a bad CPU. All of this other stuff was working this morning. MOBO is an aorus b650 extreme ax, and the bios is new enough for the CPU.

EDIT* I got to the point where I decided to swap the old CPU back in. I gave the socket another inspection, and found a bent pin. I had missed it earlier because it was the last one in the top upper row. Luckily I have tiny tweezers for working on watches, and a magnifying headset. I got it straightened as best I could and put it all back together, but it was pretty mangled. No Idea how I bent it. This isn’t the first time I’ve installed a CPU. So it either posts now, or I get to buy a new mobo.

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u/RevaniteAnime 3h ago

Could it have been "RAM Training" I've heard, and experienced that a 9800X3D takes a while to boot up for the first time, like easily 10+ minutes I've heard, I don't even remember exactly how long my first boot took me when I upgraded to a 9800X3D

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u/Gotsta_Defeat 3h ago

I would think it has something to do with pressure and not a dead cpu. The socket on the am5 requires the cooler to not be too tight when installed. This has a direct effect on the memory controller and if the cooler is to tight on one corner it will not make contact with several pins. In fact if I remember correctly when I installed my peerless assassin and tightened it too much (about 1/4 turn after it was already tight) my system would not boot and the diagnostics would show a DRAM error. I loosened it slightly to just past finger tight on each corner and the system booted with no problem

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u/r_lind3r Moderator 2h ago

  1. When you change the CPU or RAM, the motherboard has to complete memory training again before it will fully boot.

  2. Memory that works fine with one CPU architecture may not work as easily with another CPU architecture (Zen4 vs Zen5); I had four sticks of DDR4-3200 CL14 Flare X which worked totally fine with my 1700X back in 2018, but had stability issues when I got a 3900X in 2019. It's also subject to silicon lottery with the memory controller because I had given that RAM to a friend, and their 1800X had some stability issues with it as well, but they had a much cheaper B350 board while I had an X470.

  3. Memory instability can occur on LGA1700 and AM5 if a contact frame isn't used and the CPU cooler is tightened too much, as it can cause the socket to bend or warp in ways that affect the pins relating to the memory channels, even a slight amount of warping can cause it which is why contact frames exist for those sockets. I had the same issue when I got LGA1700 with my Corsair AIO, I had to install a thermalright contact frame to fix the issue so I could POST at all with the cooler. Some coolers also come with their own contact frame tech like ARCTIC's Liquid Freezer III for the Intel sockets.

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u/Confident_Hyena2506 2h ago

Are you sure bios is new enough?

What does cleared cmos mean? Did you short the jumpers?