7800X3D / ASUS B650E-PLUS: System died 2 hours after enabling EXPO. Still no POST after 3 RAM kits & ASUS RMA.

The Build (All components purchased NEW in Dec 2025): 

• CPU: AMD Ryzen 7 7800X3D 
• Motherboard: ASUS TUF GAMING B650E-PLUS WIFI 
• RAM: 32GB KLEVV CRAS V RGB (Original) / 32GB G.Skill Flare X5 (Purchased for testing 4/22/26) 
• GPU: ASUS TUF Gaming RTX 5070 Ti 
• PSU: 1000W Thermaltake Toughpower GT 

The Timeline: 

1. The Crash: Initially, I used the KLEVV CRAS V RGB kit. The system POSTed and I got into the BIOS. I enabled EXPO and began installing Windows. After about 2 hours of stability, the screen went black and it hasn't POSTed since. 
2. Professional Diagnostic: I paid a shop $125 for a diagnostic. They verified the persistent Yellow DRAM Q-LED using their own validated test RAM. They also confirmed the CPU socket was in perfect condition with zero bent pins. 
3. The ASUS RMA (Case: USI2W20290): I sent the board to ASUS. They claimed they found bent pins (contradicting the shop), "fixed" them, updated the BIOS, and returned it. 
4. The Second Attempt: Thinking the KLEVV RAM might have been the culprit, I bought a brand-new G.Skill Flare X5 kit after getting the board back from RMA. The issue persists exactly as before—stuck on the yellow DRAM light. 

The Problem: I have now ruled out three sets of RAM (KLEVV, G.Skill, and the Shop's test RAM). Since the death happened right after enabling EXPO on the original kit, I’m worried about the CPU's Integrated Memory Controller (IMC) or a motherboard failure that ASUS ignored. 

My Questions: 

• Is it possible the EXPO voltage killed the 7800X3D's IMC? 
• Given that the shop saw no bent pins before shipping, should I trust ASUS’s "repair," or is it more likely the board has a deeper electrical fault they ignored? 
• I don't have a spare AM5 board. Is there anything else I can try before I start an RMA for the CPU? 

 I'm just lost so hopefully someone can point me in the right direction. Thanks.