Ryzen 7 7700X, B650 board, 2x16GB DDR5-6000 kit in A2/B2, EXPO enabled. About one cold boot in four the BIOS reports the full 32GB, the rest of the time it says 16GB and Windows agrees. Reseating the sticks fixes it for a day or two and then it comes back. Each stick works on its own in A2, so I don't think either one is dead, and the BIOS is the newest one on the support page.
Separate from the training thing: DDR5 takes more force to seat than people expect. Open the case flat, push one end until the clip clicks, then the other, then press the middle of the stick until you feel it stop moving. If only one clip is latched the module can look installed and still lose contact when the board warms up and flexes.
Adding to this, check your standoffs while the case is open. One extra standoff under the board in the wrong spot will bow it just enough to do this and it's maddening to chase.
If it survives at JEDEC but still drops a channel, get a bright light and a phone camera on the socket contacts. AM5 is LGA, so the pins are in the board, and one flattened contact in the memory address area will kill exactly half your capacity while everything else works normally. Zoom in on the photo rather than squinting at it.
Worth doing, but photograph it before you touch anything. Bent socket contacts are usually not covered, and a board vendor that sees fresh scratch marks from tweezers will say so.
For the record: run one full pass of memtest86 per stick, per slot, so you have four data points instead of two. Takes an evening but it's the difference between guessing and knowing. Also check Task Manager reports 32GB installed rather than 32GB usable, because a hardware reserve issue looks completely different.
@airflow_amir · last mo. · 3 replies
Turn EXPO off and run at plain JEDEC 4800 for two days. If 32GB shows up every single boot at stock, the sticks and slots are fine and what you actually have is failed memory training, where the board gives up and drops a channel instead of retrying.
Then go find a setting called Memory Context Restore, usually buried in the AMD overclocking submenu, and turn it OFF. It caches the training result to speed up boot, and on early B650 boards a bad cached result gets reused on every cold start, which is exactly the on-again-off-again pattern you're describing.
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@budget_bruno · last mo.
MCR was on by default, I never touched it. Two days at 4800 and it was 32GB every boot. Just turned MCR off and put EXPO back on.
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@airflow_amir · last mo.
Leave it off permanently then. You pay maybe 10-15 extra seconds on a cold boot and get a fresh train every time. That's a good trade for not wondering where half your RAM went.
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