Do all 1150 motherboards have pci express x16 slots?

Almost certainly yes. I've never come across one that doesn't have at least 1 PCIe x16 slot.

Now WHICH graphics card that PC might support is a different story. That depends upon the PSU and internal capacity of the case, and I haven't been able to find either of those specs for the PC you linked above so you would need to find those facts out yourself before buying a new GPU.
 


Do you think i could change the power supply and replace it with a atx power supply that i already have? and it does seem to be different
 


I haven't bought it yet. I was going to buy it and put a gtx 1050 ti in there. This is what they told me when i asked about the pci-e x16 slot and the ram amount.


"We use various components for our PCs and every model has few different revisions that may have different motherboard, different brand of HDD or memory etc.

What we can confirm that all our PCs are build using well known brands such as Gigabyte, MSI, Asus, WD, Seagate."