The K1-Series CFS upgrade kit adds a second cooling fan and improved airflow management to Corsair K1-Series cases, reducing internal temperatures by roughly 10 to 15 degrees Celsius under load
The kit includes a 120mm or 140mm replacement fan (depending on your case model), a revised fan bracket, and updated cable routing guides. It is sold separately from the case itself and costs between $25 and $45. Corsair released it after the original K1-Series launch to address reports that single-fan cooling was insufficient for high-end graphics cards and processors running at full load.
You do not need the upgrade if your system runs cool enough already — check your GPU and CPU temperatures under load before spending money. If your case is sitting in a warm room, you have a high-end graphics card, or you are overclocking, the upgrade becomes more practical. The kit is straightforward to install and does not require removing the case from your desk or opening the power supply.
Key Takeaways
- The K1-Series CFS upgrade kit adds a second 120mm or 140mm fan to improve cooling capacity and reduce case temperatures by 10 to 15 degrees Celsius under sustained load.
- Installation takes 15 to 20 minutes and requires only a Phillips screwdriver and the included bracket; no case disassembly or rewiring of existing components is necessary.
- The upgrade is most useful if your GPU or CPU regularly exceeds 75 degrees Celsius under load, or if your room temperature is above 72 degrees Fahrenheit.
- Corsair sells the kit through its website and authorized retailers; verify your exact K1-Series model before ordering, as fan size and bracket type vary between versions.
Which K1-Series models are compatible
Corsair made three main versions of the K1-Series case: the K1, K1-R, and K1-R RGB. The upgrade kit works with all three, but the fan size differs. The K1 and K1-R use a 120mm fan, while the K1-R RGB uses a 140mm fan. Ordering the wrong size will not fit the bracket or mounting holes.
Check your case documentation or look at the Corsair website product page for your specific model to confirm which version you own. If you no longer have the documentation, look at the back panel of your case — the model number is usually printed there in small text, or you can contact Corsair support with a photo of the case interior.
What temperatures tell you about whether to upgrade
The main reason to add a second fan is temperature control. Use a tool like GPU-Z (for graphics cards) or HWiNFO (for CPU and GPU together) to measure your temperatures while running a demanding game or workload for at least 15 minutes. Record the peak temperature, not the idle temperature.
If your GPU stays below 70 degrees Celsius and your CPU stays below 75 degrees Celsius, your current cooling is adequate and the upgrade is optional. If either component regularly hits 80 degrees Celsius or higher, adding a second fan will noticeably reduce noise and extend component lifespan. Temperatures above 85 degrees Celsius mean the upgrade is worth doing soon, as sustained heat degrades capacitors and solder joints over time.
Room temperature matters too. If your desk is in a warm space (above 75 degrees Fahrenheit), your case will run hotter regardless of fan count. In that case, the upgrade helps more than it would in a cooler room.
How to install the upgrade kit
The installation process is designed for users with basic tools and no prior case-opening experience. Power off your system completely, unplug the power cable from the wall, and wait five minutes for capacitors to discharge. Open the case side panel by removing the two or three thumbscrews on the rear edge.
Locate the existing fan on the front or top of the case (depending on your K1-Series version). The upgrade kit includes a new bracket that mounts the second fan parallel to the first. Align the bracket with the mounting holes on the case frame, insert the four screws provided, and hand-tighten them — do not use a power drill, as over-tightening can crack the plastic frame.
Slide the new fan into the bracket with the cable facing toward the interior of the case. Connect the fan cable to an available header on your motherboard, or to a fan hub if your motherboard has no free headers. Route the cable along the existing cable paths using the adhesive cable clips included in the kit. Close the case panel, plug in the power cable, and power on to verify the new fan spins.
Fan speed and noise trade-offs
The upgrade kit does not include a fan controller, so the new fan will run at whatever speed your motherboard's BIOS settings dictate. By default, most motherboards ramp fan speed based on CPU temperature, which means the new fan may run faster than you expect during heavy load.
If noise becomes a problem, you can adjust fan curves in your BIOS or use software like Corsair iCUE (if your case has RGB lighting) to slow the fan down. Slowing the fan reduces noise but also reduces cooling capacity — the trade-off is usually worth it if you are willing to accept temperatures 5 to 10 degrees higher than maximum cooling would provide. Many users set fans to a fixed 50 to 60 percent speed and accept slightly warmer temperatures in exchange for quieter operation.
Where to buy and what to expect for cost
Corsair sells the K1-Series CFS upgrade kit directly through its website store and through authorized retailers including Amazon, Newegg, and B&H Photo. Prices typically range from $25 to $45 depending on the fan size and current promotions. Shipping usually takes 3 to 7 business days from the retailer.
Before ordering, verify the exact model number of your case and confirm which fan size the kit includes. Some retailers list both the 120mm and 140mm versions under similar product names, and ordering the wrong one means a return and reorder delay. Check the product page specifications or contact the retailer's support team if the listing is unclear.
Alternatives if the upgrade kit is unavailable
If the official Corsair kit is out of stock or discontinued, you can purchase a compatible third-party 120mm or 140mm fan separately and mount it using the existing bracket holes on your case. Brands like Noctua, Be Quiet, and Arctic make high-quality replacement fans in both sizes. This approach costs $15 to $30 and gives you more choice in fan noise and performance characteristics.
The downside is that you lose the cable routing guides and bracket that come with the official kit, so installation takes longer and cable management may look less polished. If you are comfortable with basic case work and do not mind spending extra time on routing, this is a practical alternative. If you prefer a complete kit with all parts designed to fit together, wait for the official kit to come back in stock or order it directly from Corsair.
Frequently Asked Questions
Will adding a second fan make my system noticeably quieter?
Not automatically. Two fans running at the same speed as one will actually be slightly louder because there are two noise sources. The benefit is that each fan can run slower to achieve the same cooling, which reduces overall noise. If you adjust your BIOS fan curve to run both fans at 40 to 50 percent speed instead of one fan at 80 percent, the system will be quieter and cooler.
Do I need to update my BIOS or drivers after installing the kit?
No. The upgrade kit is a passive hardware addition — it does not require firmware updates or driver installation. Your motherboard will recognize the new fan automatically once you plug it in. If the fan does not spin, check that the cable is fully seated in the motherboard header and that your BIOS fan settings are not set to a minimum speed below the fan's starting threshold.
Can I install the upgrade kit myself, or do I need a technician?
The installation is straightforward enough for most users with a screwdriver and 20 minutes of time. No soldering, no BIOS flashing, and no component removal beyond opening the case panel is required. If you have never opened a computer case before, watch a video of the installation first to see the process, but there is no technical barrier to doing it yourself.
What if my case does not have a free fan header on the motherboard?
You can use a fan hub or splitter cable to connect multiple fans to a single header. Corsair and other manufacturers sell 4-pin PWM fan hubs for $10 to $20 that allow you to connect up to four fans to one motherboard header. Alternatively, some cases include a built-in fan hub on the back panel that you can plug into instead of the motherboard directly.
Will the upgrade kit void my case warranty?
No. Adding a fan is considered a user upgrade and does not void the case warranty. Corsair's warranty covers manufacturing defects in the case frame and original components, not damage caused by user modifications. Keep your receipt for the upgrade kit in case you need to reference it, but there is no registration or notification required.