On most Asus notebooks, the CMOS (RTC) battery sits under the bottom cover near the main battery or RAM; some models hide it under the keyboard.
Find The RTC Battery On Your Asus Notebook: Fast Checks
Every model family places the tiny backup cell a bit differently. The good news: you can pinpoint it in minutes. Start by confirming your exact model name (label on the bottom shell or in BIOS). Then use the steps below to track the part without tearing the whole machine apart.
What The RTC Battery Does
This coin cell or cabled pack feeds the real-time clock and stores firmware settings when the laptop is unplugged. When it fades, the clock drifts, the BIOS prompts to reset, and power-on can slow or loop.
Check Your Exact Location In Minutes (Model-Specific)
1) Look Up Your Model’s Repair Or User Manual
Go to the ASUS Download Center and enter your model. Open the service or repair manual if available. Search the PDF for the strings “RTC battery,” “CMOS,” or “CLRTC”. Many manuals draw the part and note if it’s a coin cell on top of the board, a wired pack taped to the chassis, or a unit on the underside of the motherboard.
2) Scan Photo Guides For Your Exact Chassis
Community repair guides are handy for spotting placement before you open your unit. Look for a guide that matches your suffix (such as GA401QM vs. GA401Q). If a guide shows an RTC module on the underside, plan for a full motherboard lift.
Safe Prep Before You Open Anything
Work on a clean table. Back up data. Power off the laptop and unplug the charger. If your model has a battery disconnect pinhole, trigger it. If not, remove the bottom cover and disconnect the main battery cable before touching other parts. Touch a grounded metal surface or wear a wrist strap. Hold the power button for ten seconds to drain residual charge.
Where You’ll Usually Find It By Series
Vivobook And Everyday 14/15-Inch Chassis
Typical layout: a silver coin cell in a small plastic holder or a tiny two-wire pack taped near the battery bay or Wi-Fi card. Access is simple once the base cover is off. Some X415/X409 variants use a cabled RTC pack.
Zenbook And Thin-And-Light Models
Many ultrathin units use a slim wired RTC pack taped under a mylar sheet near the speakers or battery. A few designs place it on the underside of the board, which means a full board flip.
TUF Gaming And ROG Zephyrus
You’ll often see a small connector labeled RTC on the board and a black wrapped coin cell or pack nearby. On several Zephyrus boards the part sits along the edge by memory or speakers. Certain gaming boards place it on the board’s back, requiring board removal.
Older And Budget Lines
Legacy models may use a standard CR2032 in a holder. It can sit under the palm rest or on the underside of the board. Expect more screws and ribbon cables on these frames.
Step-By-Step: Access And Replace The RTC Battery
1) Remove the base screws. Some are hidden under the rear feet. Keep lengths sorted.
2) Pry the bottom cover with a plastic tool. Start at a hinge corner and release clips.
3) Disconnect the main battery first. Wait ten seconds.
4) Spot the RTC module. It’s either a coin cell in a holder or a small black wrapped cell with a two-pin cable labeled RTC.
5) If it’s on the top side, lift any tape and unplug the tiny connector. If it’s on the back side, remove fans, SSD, and the board with care, then access the part.
6) Replace like-for-like: coin cell holder → CR2032; wired pack → the same connector type and voltage. Match polarity.
7) Reassemble. Reconnect the main battery last. Boot to BIOS and set date/time.
After The Swap: What To Expect
The first boot may take longer while firmware rebuilds defaults. Set the clock and boot order. If you cleared settings, enable any storage controller mode you used before.
Can Some Asus Laptops Lack A Separate RTC Battery?
Yes. A few designs rely on the main battery to keep RTC data. Symptoms look similar when that pack is flat. If your manual shows no discrete RTC module, charge the laptop, update BIOS, and retest before chasing a part that isn’t there.
Model Examples You Can Use For Reference
• ROG Zephyrus GA401: the service guide lists an RTC battery module with a small connector and removal step numbers.
• VivoBook X415/X409 series: repair manuals show a cabled RTC pack near the main battery.
• Legacy X551/D550 lines: photo guides show a standard coin cell on or under the board.
When To Stop And Get Service
If the RTC part appears soldered, buried under the keyboard deck, or glued to sensor harnesses, don’t force it. Order the exact harness by model, or book an official repair to avoid board damage. Warranty work should go through ASUS.
Quick Reference Table: Typical Locations And Access
Use this table to plan your approach. It lists common families, the usual RTC style, and what it takes to reach it.
| Series / Example | RTC Style | Access Level |
|---|---|---|
| Vivobook X415/X409 | Wired RTC pack | Remove base, top-side access |
| Zenbook UX425/UX435 | Slim wired pack | Remove base; on some, board flip |
| ROG Zephyrus GA401 | Wired RTC with plug | Remove base; sometimes under shields |
| Older X551/D550 | CR2032 in holder | Base off; some need board flip |
Tips That Save Time And Screws
Label your screws by row as you go. Photograph cable routes. If the laptop won’t power after reassembly, reseat the battery connector and the keyboard ribbon. A no-power state after an RTC swap is usually a loose connector, not a dead board.
Signs That Point To The RTC Cell
You set the time and it drifts after every shutdown. The BIOS forgets boot order or shows a checksum prompt. The laptop powers on, fans spin, then it loops back off and on until you save settings. These are classic hints that backup power is weak.
Tools And Parts You’ll Need
• Precision Phillips screwdriver set
• Plastic opening picks or a guitar pick
• ESD strap or a grounded metal object within reach
• Small tweezers
• New RTC coin cell (CR2032) for holder-type designs or a matching wired pack for your model
• Low-tack tape to secure a loose lead, if the manual shows tape there
• Small containers for screws
Model Lookup: Fast Path To The Right PDF
On the support page, enter the full model (such as UX425EA, GA401QM, or X415DA). Open the manual and check the disassembly section. You’ll often see a page titled Disassembly Procedure or Battery Module. If a step says “Disconnect the RTC battery connector,” you’ve found your target and the photo shows its spot.
Opening The Base Without Breaking Clips
Many Asus bases use a mix of long and short screws. A few hide screws under rubber feet. Lift the rear feet with a thin pick, then store them adhesive-side up so they can go back. Slide a pick along the seam and listen for gentle clicks as the clips release. Don’t twist metal tools between panels.
Top-Side Versus Back-Side Placement
Top-side means you can see the part once the cover is off. Back-side means it sits on the underside of the motherboard. If it’s back-side, photograph every cable and heatsink screw pattern, then lift the board with the I/O edge first. Keep thermal pads clean and in the same places when you reinstall.
Setting BIOS After Replacement
Enter BIOS on first boot (usually F2 or Del). Set date and time. Check storage settings, boot order, and any Secure Boot choice you used. Save and reboot. In Windows, verify time sync and run a shutdown test. If the clock holds across two cold starts, the fix worked.
If You Still Can’t Find The Module
Some ultra-thin systems integrate backup power into the main pack or place a tiny cell under the keyboard deck. If the manual and guides show no separate part, don’t chase one. Replace or charge the main pack, update BIOS, and recheck.
Small Details That Prevent Headaches
Match the connector. Asus uses more than one tiny two-pin style. Order by exact part number from the manual or a trusted parts house. If the old pack is taped, reuse fresh tape in the same spots. Don’t stretch speaker or Wi-Fi antenna leads while reaching for the plug. Keep original pads aligned. Carefully.
Common Mistakes And Quick Fixes
• The keyboard doesn’t work after reassembly: reseat the ribbon and lock the latch.
• There’s no display: check the display cable and reconnect the battery.
• Fans ramp hard: a thermal pad moved; place it back and tighten heatsink screws in a cross pattern.
• Time still resets: test the new cell with a meter, and confirm the plug is fully seated.
Model Clues You Can Spot Without A Manual
Look near serviceable areas. If your model has a single RAM slot, scan the open space opposite that slot for a taped pack. If there’s soldered memory and only an M.2 bay, check the speaker cavities for a small wrapped cell. On boards with a fan on the left and battery spanning the front, the RTC often sits on the right edge by the Wi-Fi card.
If you see a small two-wire lead heading under a mylar square, that’s usually it. Lift the tape gently and you’ll find the tiny connector underneath.