Estimated Operational MTBF Methodology
How we turn part-level failure data into one reliability number. And why cooling fans and CPUs are treated differently from every other part.
Worked example: a baseline industrial motherboard system. See section 08.
SuperLogics can provide an Estimated Operational MTBF for a baseline system or a project build. Customers use this number during design reviews, reliability studies, and procurement.
Estimated Operational MTBF is an estimate of how long a system runs between hardware failures that stop normal operation. It is based on a set configuration and the assumptions below. It is not a warranty, and it is not a promise of service life.
Summary
Estimated Operational MTBF is the estimated time between hardware failures that stop a system from running normally. It applies to a set baseline configuration.
How our model differs
- It counts outages, not every part failure. A simple MTBF counts any failed part as a failure.
- Serviceable parts are treated differently. A cooling fan can fail without stopping the system, so it is not counted as an outage.
- It reflects what we see in the field. Our model weighs the parts that actually cause downtime.
What Estimated Operational MTBF Means
This number estimates the time between hardware failures that would stop the system from running.
That is not the same as a hardware service-event MTBF. A service-event MTBF counts every failed part as a failure event. In practice, one failed part often does not take a system down.
Failures that usually do not stop operation
- A cooling fan, when other fans still cool the system
- One module in a redundant power supply
- One drive in a mirrored storage set
Each of these creates a service need or a reduced-redundancy state. The system keeps running. We use the term Estimated Operational MTBF to separate this customer-facing number from the stricter part-service calculation.
↑ Back to Quick LinksCalculation Method
We use a component-level FIT roll-up. FIT stands for failures in time. One FIT is one failure per billion operating hours.
The four steps
System FIT = Sum of included component FIT values
Estimated Operational MTBF = 1,000,000,000 ÷ System FIT
Estimated years of 24/7 use = Estimated Operational MTBF ÷ 8,760
Where the numbers come from
- Published MTBF or FIT data from the part maker, when it is available
- Category estimates for similar parts, when it is not
- Our own field experience with systems that are installed and run properly
Baseline Assumptions
Unless we state otherwise, every SuperLogics MTBF number assumes the following.
System and environment
- Baseline system configuration
- Controlled indoor environment
- Normal operating temperature and airflow
- Standard duty cycle for the system class
- No customer-added hardware
- Proper installation and maintenance
Calculation rules
- Cooling fans are left out of the calculation
- CPU failures count as low-contribution events
- Component-level FIT roll-up, using maker data, category estimates, and field experience where needed
Cooling Fan Treatment
Cooling fans are left out of the standard calculation. Here is why.
- Every system is designed with enough cooling for its configuration
- A supported baseline system runs properly on the standard minimum fan count
- Extra fans add thermal margin, better airflow, or easier service
CPU Treatment
CPU failures are not a main driver of our standard model.
In systems that are installed and run properly, CPU failures are rare. We see far more service calls for other parts.
More common service items
- Power supplies
- Storage devices
- Memory
- Motherboards
- Add-in cards
- Customer or environment related issues
So the standard model treats CPU failures as low-contribution events. We do not publish a separate CPU FIT value. If your project needs a processor-specific study, we can review the processor documentation and your assumptions separately.
↑ Back to Quick LinksExample Component Assumptions
These are sample values we may use when part-specific data is not available. We replace them with the part maker's own figures whenever reliable documentation exists.
| Component Category | Example MTBF Assumption | Example FIT |
|---|---|---|
| Typical retail motherboard | 250,000 hours | 4,000 FIT |
| Industrial motherboard | 350,000 hours | 2,857 FIT |
| Server motherboard | 400,000 hours | 2,500 FIT |
| CPU | Counted as a low-contribution event | Not separately published |
| DDR4/DDR5 memory module | 3,000,000 hours each | 333 FIT each |
| NVMe SSD | 1,500,000 hours | 667 FIT |
| Standard SuperLogics power supply (baseline / worst case) | 100,000 hours | 10,000 FIT |
| Cooling fans | Left out of the standard calculation | Excluded |
Example Baseline MTBF Values
Each example below uses the same parts list: one motherboard, one CPU, two memory modules, one SSD, and one power supply rated at 100,000 hours. Cooling fans are left out.
| System Type | Estimated System FIT | Est. Operational MTBF (excl. cooling fans) | Equivalent 24/7 Use |
|---|---|---|---|
| Typical retail motherboard system | 16,334 FIT | 61,000 hours | 7.0 years |
| Industrial motherboard system | 15,191 FIT | 66,000 hours | 7.5 years |
| Xeon/server motherboard system | 14,334 FIT | 70,000 hours | 8.0 years |
Example Product Page Statement
That value is a guide figure for the baseline configuration. It comes from the component-level FIT roll-up described above. It estimates the time between hardware failures that would stop normal operation, with cooling fans left out.
What the baseline includes
- One industrial motherboard
- One CPU
- Two memory modules
- One SSD
- One power supply
Fans are left out because a supported baseline system is built to run on the standard minimum fan count. Extra cooling counts as margin or as a service event, not as an outage.
Real-world results vary. Final configuration, temperature, airflow, workload, site conditions, maintenance, and added parts all play a role.
↑ Back to Quick LinksConfiguration Changes
Each MTBF value belongs to one configuration. Change the build and the number changes too.
Changes that affect the estimate
- Motherboard type
- Number of memory modules
- Number and type of SSDs or hard drives
- Power supply model
- Redundant power configuration
- RAID or mirrored storage
- Add-in cards
- GPUs
- Specialized I/O cards
- Customer-installed hardware
- Project-specific processor requirements, when they apply
Send us the final bill of materials for a custom build. We will update the estimate once we have enough part detail.
↑ Back to Quick LinksImportant Limitations
Estimated Operational MTBF is not a warranty. It does not guarantee service life, and it does not promise uninterrupted operation.
MTBF is a statistical estimate built on assumptions and part data. Real-world reliability varies with the final build, heat, airflow, workload, site conditions, power quality, maintenance, install quality, and any parts you add.
The "equivalent 24/7 use" figure is there to make the hours easier to picture. It does not mean a given system will fail after that many years. It also does not mean the system will run that long without service.
Use these values for design-phase analysis and general planning. Review project-specific requirements with us before you place an order.
Customer Requests
Need MTBF documentation for a specific system? Send us these four things.
- The SuperLogics part number
- The configuration you need
- The operating environment
- Any project-specific reliability requirements
We will tell you whether the published baseline applies, or whether your build needs its own review.
↑ Back to Quick LinksNeed MTBF documentation for a specific system?
We can confirm whether the published baseline applies to your build, or run a full review from your bill of materials.