let str = "2x PCI-e 4.0 x1, 2x PCI-e 4.0 x16";
let objects = str.split(", ");
let result = {};
objects.forEach(o => {
    let o2 = o.split("x ");
    let amount = Number(o2.shift());
    result[o2.join("")] = amount;
});
console.log(result);