Scalable system for high-performance computer, comprising • a plurality of motherboard chassis inserted in a computer rack mounting kit , • each motherboard chassis , called inner chassis , having front and rear longitudinal ends, being open at these ends, and being configured to receive at least one motherboard module comprising motherboard connectors, said motherboard module being inserted by a first longitudinal end of the inner chassis , • said plurality of inner chassis forming a stack of inner chassis, the stack being configured to receive an outer floating bracket chassis , said outer floating bracket chassis being inserted by a second longitudinal end of each inner chassis forming the stack of inner chassis, • said outer floating bracket chassis housing a cable box , configured for connecting to each other the motherboard connectors of a plurality of motherboard modules arranged in the stack of inner chassis , and at least one double floating bracket housing cable connectors of the cables of said cable box , • the system being characterized in that said double floating bracket comprises : i. first floating attachment means configured to guide the double floating bracket in the outer floating bracket chassis by aligning upward and downward said double floating bracket with an inner chassis , ii. second floating attachment means configured to align the cable connectors of the cables of said cable box with motherboard connectors of each of the motherboard modules . • a plurality of motherboard chassis inserted in a computer rack mounting kit , • each motherboard chassis , called inner chassis , having front and rear longitudinal ends, being open at these ends, and being configured to receive at least one motherboard module comprising motherboard connectors, said motherboard module being inserted by a first longitudinal end of the inner chassis , • said plurality of inner chassis forming a stack of inner chassis, the stack being configured to receive an outer floating bracket chassis , said outer floating bracket chassis being inserted by a second longitudinal end of each inner chassis forming the stack of inner chassis, • said outer floating bracket chassis housing a cable box , configured for connecting to each other the motherboard connectors of a plurality of motherboard modules arranged in the stack of inner chassis , and at least one double floating bracket housing cable connectors of the cables of said cable box , • the system being characterized in that said double floating bracket comprises : i. first floating attachment means configured to guide the double floating bracket in the outer floating bracket chassis by aligning upward and downward said double floating bracket with an inner chassis , ii. second floating attachment means configured to align the cable connectors of the cables of said cable box with motherboard connectors of each of the motherboard modules . i. first floating attachment means configured to guide the double floating bracket in the outer floating bracket chassis by aligning upward and downward said double floating bracket with an inner chassis , ii. second floating attachment means configured to align the cable connectors of the cables of said cable box with motherboard connectors of each of the motherboard modules . <EOS>