and using same RJ45s cables to connect the switch to my PC,
You're OK up this point, but you won't be able to use RJ45 cables to connect the Mikrotik switch to your computers, because you've already used the one and only RJ45 Ethernet port on the Mikrotik.
The other four ports on the Mikrotik are all SFP+ 10Gigabit, for Direct Attached Copper cable or Fibre Optic transceivers and OM3 cable. OM3 might work at up to 300m (1,000ft) at 10Gb/s, although most ready-made OM3 cables stop at 200m.
The whole point of this tiny Mikrotik switch is to link four devices together at 10Gb/s using SFP+, with an optional fifth device running at 1Gb/s on RJ45 Ethernet. This could be used as a monitor port, a PoE port, or as I use it, a 1Gb/s output to another switch for internet on computers lacking 10G NICs.
I connect one of the four SFP+ ports on the Mikrotik via a 30m fibre link to the computer room upstairs, where my optical 'fibre-to-the-premises' broadband router is situated.
The output from my broadband router upstairs is standard 1G Ethernet. I pay for the slowest 100Mbit/s broadband option, because I'm too impecunious to afford $100 per month for 1,000Mb/s broadband.
https://www.broadbandsearch.net/definitions/fiber-to-the-premise
I run a couple of DAC cables from my Mikrotik (downstairs) to two HP servers, which at nearly 50kg each, are too heavy to drag up a flight of stairs to the computer room (and it saves the floor from an extra 100kg weight). The remaining SFP+ output is shared between various other machines.
I have a 10Gb 10-port Netgear switch upstairs, which links to the Mikrotik downstairs using a 30m OM3 fibre optic cable with SFP+ transceivers at either end.
A few examples of kit.
This is a typical DAC cable, 2m long. You can get longer or shorter DACs, depending on where you position the Mikrotik switch. Make sure the DACs are rated at 10G, not 1G.
https://www.amazon.com/10G-SFP-DAC-Cable-SFP-H10GB-CU2M/dp/B00U8BL09Q
Being Copper wire based, DACs work over much shorter distances than fibre, so they're typically used as short (0.5m) patch leads in 19" equipment racks. I buy 2m (6ft) and 3m (10ft) DACs, but I doubt you'll find many DACs over 5m (16ft). At this length most people use fibre.
This is a typical OM3 LC-LC Fibre Optic cable, available in many different lengths up to 200m.
https://www.amazon.com/FLYPROFiber-Fiber-Patch-Length-Options/dp/B08974BY91
Below are a couple of 10G LC Transceivers. It's important to buy 10G, not 1G transceivers, otherwise you won't get 10Gb/s over the link. 10G transceivers can be more expensive than 1G.
https://www.amazon.com/Cable-Matters-10GBASE-LR-Transceiver-Supermicro/dp/B07TTKHG6T
I buy brand new OM3 cables, but second-hand DACs and SFP+ transceivers. Take care not to bend OM3. It doesn't take kindly to sharp right angle bends.
System Connection
After plugging each end of the OM3 fibre into a transceiver, you push the transceivers into the SFP+ ports on the Mikrotik switch and the Solarflare 5122 NICs in your desktop computers.
The whole point of the exercise is to connect two (or more) computers together at 10Gb/s, to achieve data transfers up to 10x the speed of 1G Ethernet.
The slowest drive in the chain determines the maximum speed across the link. Hence on my 8-disk RAID-Z2 servers, that's around 140MB/s (Mega bytes/s), not much faster than Gigabit. Between two computers containing NVMe drives, I see over 600MB/s at times. Fast enough for my needs.
2.5G and 5G Ethernet chipsets are becoming more common, but it's rare to find 10G Ethernet built into motherboards intended for home use. The price of 10G Ethernet cards has come down, but I paid roughly $125 each for four Asus XG-C100C cards back in 2018. The 10-port Netgear switch (8 x 10G RJ45, 2 x 10G SFP+) was another $500.
I changed from relatively expensive 10G Ethernet to cheaper 10G optical fibre in 2020, because high quality ex-server SFP+ NICs, transceivers and DACs were available on the second hand market. Affordable multi-port 10G server switches tend to be power hungry, which is why I bought the Mikrotik. I don't need 12 or 24 SFP+ ports on a Cisco managed switch.
If you ever feel like going faster, there's 25G, 40G and 100G networking over OM4/OM5 fibre.
https://forums.servethehome.com/index.php?threads/cheap-40gbe-at-home-too-good-to-be-true.26143/