I thought tuning the memory was something I did to the memory, not something intrinsic to the memory.
Looking at the Kingston site for memory kits for a threadripper build ; I hit https://shop.kingston.com/collections/memory/products/renegade-pro-ddr5-desktop-memory?variant=43539670171840. I can choose from xmp profile or expo profile.
The renegade 16 gb 5600 kit of 4 KF556R36RBK4-64 is 522.99. Switch to renegade 16 gb expo 5600 kit of 4 KF556R28RBEK4-64 price 323.99.
Is there a physical reason that the memory has, to explain why the difference (different sku, different price ) when the only thing I changed is the tuning profile?
XMP and EXPO are essentially prebuilt profiles built into the DRAM. XMP has always been an Intel profile, AMD boards just supported it due to not having their own. Now they do have their own - EXPO. You should get XMP for intel, or EXPO for AMD; however it’s not the biggest difference.
I think what you’re seeing is a pricing error, or a quirk based on available stock. Bot pricing can do some weird stuff. Checking on amazon these are basically the same price locally.
Using XMP on AMD systems is generally not recommended, the subtimings do not carry over so you’d be falling back on the board defaults. And XMP kits aren’t going to have AMD voltage settings in their profile, either. I think just the main memory voltage carries over.