The Xtreme Power Conversion M90S-6S (with M90S-RMK rack-mount kit) and the APC Symmetra LX SYA16K16RMP are modular, true online, double-conversion UPS systems designed to protect mission-critical single-phase rack-mounted loads.
While both platforms support hot-swappable modules and scalable architectures, the M90S-6S is an active, current-generation platform that delivers significantly higher usable power, greater efficiency, broader scalability, and assured long-term expansion and factory support, whereas the Symmetra LX is a discontinued legacy system.
18 kVA Modular Rack-Mounted UPS Comparison
| Feature | XTREME POWER M90S-6S (with M90S-RMK) | APC Symmetra LX SYA16K16RMP | XPCC Advantage |
| Product Status | Active production | Discontinued (Aug 26, 2025) | Long-term platform availability |
| Capacity | 18 kVA / 18 kW (unity PF) | 16 kVA / 12.8 kW (0.8 PF) | ~40% more usable power |
| Topology | Online Double Conversion | Online Double Conversion | Equivalent protection |
| Modularity / Scalability | 6–24 kVA in 6 kVA increments (up to 18 kVA N+1) | 4–16 kVA N+1 in 4 kVA increments | Higher maximum capacity |
| Rack Space Required | 26U (45.5 in) | 19U (32.9 in) | Higher usable kW per rack |
| Efficiency | Up to 98% (ECO) / 93% online | ~88.7% online | Lower operating cost & heat |
| Internal Runtime | Up to 9 min @ 18 kW | Up to 6 min @ 12.8 kW | Longer internal runtime |
| Maintenance Bypass | Standard | Standard | Equivalent serviceability |
| Module Slot Flexibility | Universal slots (power or battery) | Dedicated power & battery slots | Simpler expansion & sparing |
| Warranty | 3-year repair or replace | 2-year repair or replace | Longer standard warranty |
Printable Comparison PDF
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Where the M90S-6S Excels
- Replacing discontinued Symmetra LX rack systems
- Deployments requiring full usable kW output (unity power factor)
- Facilities prioritizing higher efficiency and reduced cooling load
- Installations needing flexible power vs battery module allocation
- Organizations planning future expansion with assured factory support
When APC Symmetra LX May Still Be in Use
- Existing deployments with installed spare modules
- Short-term environments where no expansion is planned
- Legacy systems awaiting scheduled modernization or replacement
Who Should Choose Which
Choose Xtreme Power Conversion M90S-6S if you need:
- An active, long-term supported modular UPS platform
- Significantly higher usable power in the 18 kVA class
- Greater efficiency to reduce operating and cooling costs
- Simpler expansion and sparing with universal module slots
- Longer standard warranty coverage
Choose APC Symmetra LX if you need:
- Temporary continuation of an existing legacy deployment
- No requirement for future expansion or factory support
Ideal Applications
- Enterprise and edge data-center racks
- Healthcare and laboratory environments
- Industrial and manufacturing operations
- Government and education infrastructure
- Symmetra LX rack-mount replacement projects
Plan with Confidence
Request a Quote
Speak with an Xtreme Power Conversion specialist to size the right M90S-6S modular configuration and plan a smooth migration from legacy Symmetra LX systems.
Xtreme Power Conversion
Phone: (800) 582-4524