I bought a 'fully loaded' server, RAM was mismatched

For what it's worth, hot take: eBay server listings are SPF records for hardware. They look authoritative until you actually check.

Bought a "128GB" Dell from a seller with 4.9 stars. BIOS shows 128GB installed. OS shows 96GB usable. DIMMs are 16GB dual-rank + 16GB single-rank mixed in channels. Intel memory guide is clear: matched ranking required for full population.

Seller: "I just sell what the sticker says." PayPal sided with me in 48 hours.

Check your ranking before you check your feelings. No amount of DMARC alignment will save you from mismatched quad-channel configs.

Actually I had same problem with supermicro board seller said 64GB but it was 48GB usable because ranking mismatch (´・ω・｀) basically I was so angry but too lazy to return so I just use it for backup server lol. Next time I will check rank before buy