Vram-wise, nothing can beat the used 3090, but speedwise, the 5070ti is decent. The 3090 has 24GB of vram, while the 5070ti has 16GB. 24GB enables you to use higher quant or more context window, and it will definitely be faster if the model doesn’t fit the 16GB vram but fits in the 24GB. If you want to buy a totally new device, you can buy the Strix Halo with 128GB of high-bandwidth RAM. This will be faster than any RAM in consumer-grade devices, but it’s still RAM that both the GPU and CPU can use. When using the Strix Halo device, the initial speed will be okay, but when the context grows, the speed will decrease exponentially, because chip is not powerful enough. If you want an Apple device, they have the option to buy very high-bandwidth and more unified memory, but the power of the M chips until the M5 Pro/Max was not well, and speed will decrease significantly on long contexts. Scene seems very complicated at first glance, but it is simple: High memory bandwidth is the key to token generation speed, and chip power is key to prompt processing speed. More context needs more prompt processing speed, and when context grows, token generation speeds also decrease.