Quick question about my motherboard pcie slots

[loganjrussell]

I have the x299 tomahawk arctic motherboard and I recently purchased an MSI 2080ti and it does not fit in my PCIe 1 slot but fits in the pcie4, they both are said to 3.0 x16 speed but in the manual, it says I have to use PCIe 1 for optimal performance. Can anybody confirm this, depends if I need to buy a new heat sync thanks!

Pictures to reference
https://gyazo.com/d5d3239334298a686193a089972f3538
https://gyazo.com/07404cb55b26dc34df9f6621f89d4a83

 

[A_Goat]

It will work fine in slot 4, you won't be able to tell the difference in performance.

The difference is so negligible that it would be quite silly to spend any money on replacing anything for just that reason.