Blade computer system

1. A blade computer system comprising:

a rack;

a first plurality of side-by-side computer blades within the rack, each computer blade of the first plurality of side-by-side computer blades having a major dimension extending along a first axis;

a first connectivity module extending across and perpendicular to the first axis across, the first connectivity module spanning the first plurality of side-by-side computer blades and being connected to an end of each computer blade, the first connectivity module to connect each computer blade to switches; and

at least one first power supply-fan unit extending perpendicular to the first axis, the at least one power supply-fan unit directly connected to the end of each computer blade,

wherein an airflow path is defined across the first plurality of side-by-side computer blades, into the first connectivity module, and into the power supply-fan unit.

2. The blade computer system of claim 1 , wherein the at least one first power supply-fan unit is to create a substantially unidirectional flow along the first axis across the first plurality of side-by-side computer blades and across the first connectivity module.

3. The blade computer system of claim 1 further comprising:

a second plurality of side-by-side computer blades within the rack, each of the second plurality of side-by-side computer blades having a major dimension extending along the first axis; and

at least one second power supply-fan unit extending perpendicular to the first axis, the at least one second power supply-fan unit being directly connected to each of the second plurality of side-by-side computer blades along ends of the second plurality of side-by-side computer blades such that the at least one second power supply-fan unit draws air across the second plurality of side-by-side blades and into the first connectivity module;

wherein each of the at least one first power supply-fan unit has a second dimension along the first axis; and

wherein the at least one second power supply-fan unit has a third dimension along the first axis greater than the second dimension.

4. The blade computer system of claim 1 further comprising a rack interconnect supported by the rack and including switches,

wherein the first connectivity module includes:

an enclosure;

a plurality of first optical connectors directly connected to each of the first plurality of side-by-side computer blades;

optical ribbons connected to the first connectors; and

external optical ports supported by the enclosure, connected to the optical ribbons and optically connected to the rack interconnect.

5. The blade computer system of claim 4 , wherein the first connectivity module further includes:

at least one electrical midplane supported by the enclosure and electrically connected to the first plurality of side-by-side computer blades;

a first printed circuit assembly within the enclosure and connected to the at least one electrical midplane, the printed circuit assembly including first management circuitry; and

first external electrical ports supported by the enclosure and connected to the first printed circuit assembly.

6. The blade computer system of claim 5 further comprising:

a second printed circuit assembly within the enclosure connected to the at least one electrical midplane, the second printed circuit assembly including second management circuitry; and

second external electrical ports supported by the enclosure and connected to the second printed circuit assembly.

7. The blade computer system of claim 5 further comprising:

a low total bandwidth device; and

an electrical connection from the low total bandwidth device to the first external electrical ports of the first connectivity module.

8. The blade computer system of claim 5 further comprising a direct CPU-to-CPU coherency domain connection within the enclosure connecting first and second blades of the first plurality of side-by-side computer blades.

9. The blade computer system of claim 1 further comprising a second connectivity module extending across and perpendicular to the first axis, the second connectivity module extending adjacent the first connectivity module while being connected to the end of each computer blade, the second connectivity module to connect each computer blade of the second plurality of side-by-side computer blades to switches.

10. The blade computer system of claim 9 , wherein each of the first connectivity module and the second connectivity module includes:

an enclosure;

a plurality of first optical connectors directly connected to each of the first plurality of side-by-side computer blades;

optical ribbons connected to the first connectors; and

external optical ports supported by the enclosure, connected to the optical ribbons and optically connected to the rack interconnect.

11. The blade computer system of claim 1 , wherein each of the first plurality of side-by-side computer blades is connected to first and second power supplies of the first plurality of power supply-fan units.

12. The blade computer system of claim 1 , wherein a first number of the first plurality of side-by-side computer blades is connected to four of the first plurality of power supply-fan units and wherein a second number of the first plurality of side-by-side computer blades is connected to less than four of the first plurality of power supply-fan units.

13. The blade computer system of claim 1 , wherein the first connectivity module includes:

an enclosure;

at least one electrical midplane supported by the enclosure and electrically connected to the first plurality of side-by-side computer blades;

a first printed circuit assembly within the enclosure connected to the at least one electrical midplane, the printed circuit assembly including management circuitry; and

first external electrical ports supported by the enclosure and connected to the first printed circuit assembly.

14. The blade computer system of claim 1 , wherein the at least one first power supply-fan unit comprises a plurality of power supply-fan units electrically connected to a same blade of the first plurality of side-by-side computer blades.

15. A method comprising:

connecting a power supply-fan unit directly to a plurality of side-by-side computer blades along ends of the computer blades;

connecting a connectivity module directly to ends of the computer blades and positioned to span the plurality of side-by-side computer blades, the connectivity module to connect the computer blades to rack interconnects; and

drawing air with the power supply-fan unit along an airflow path defined across the plurality of computer blades and into the connectivity module.