Mostly capacity beyond that top-line number. Both cap out at 5 Gbps, but the 640 handles several times more SSL terminations per second and supports up to 250 real servers instead of 100, so it's built for a much larger and busier server farm even though the headline throughput matches.

Fitting the processing headroom for 250 servers and a much higher SSL termination rate takes more room than the 1U Mini chassis used on the 340 through 540. The larger 1U Fullsize chassis is what makes that extra capacity possible.

Not on the base 640 model. It ships with eight 1 Gigabit copper ports; 10 Gigabit copper and fiber options are available on the 641 and 642 variants if your uplinks need that extra bandwidth.

Yes. Global Server Load Balancing lets the 640 direct traffic across multiple data centers based on proximity or failover rules, which matters once you're running application infrastructure in more than one location.

For most companies, it's more than needed. If you're running well under 250 servers, the 340 through 540 will cover you at a lower cost with the same load balancing, SSL offload, and attack protection. Talk to a rep and we'll size it honestly rather than sell you more capacity than you need.