This worked for me:
1 - Open Warehouse.
2 - Click on “Ship Modifiers” and then select Computer.
3 - On the top menu click the My Items button
4 - You will see an item called “Overclocked CPU I”, or whatever installed on your Jericho ship. Right click it and sell.
5 - Make sure that a Jeticho ship is selected, then click the button Shop on the top menu and then select the “fits ship” option.
6 - Buy back the item sold in step 4, right click it and upgrade to Mk 2.
7 - Open the Equipment tab (press F2). The ship modifier slot will be empty so you need to select the item upgraded in step 6 and equip it.
Have fun!