223:
100:
92:
50:
208:
152:
because, after the system loses power, it does retain state by virtue of the CMOS battery. When the battery fails, BIOS settings are reset to their defaults. The battery can also be used to power a real time clock (RTC) and the RTC, NVRAM and battery may be integrated into a single component. The
311:
and older IBM PC compatibles), which serves the same purpose. These motherboards often have a four pin straight header, with pin 2 missing, for connecting to an external 3.6v battery, such as the
Tadiran TL-5242/W, when their soldered-on batteries run out. Ni–Cd batteries have a tendency to
268:, is not rechargeable and trying to do so may result in an explosion. Motherboards have circuitry preventing batteries from being charged and discharged when a motherboard is powered on. Other common battery cell types can last significantly longer or shorter periods, such as the smaller
272:
which will generally last about 40% less time than CR2032. Higher temperatures and longer power-off time will shorten battery cell life. When replacing the battery cell, the system time and CMOS
553:
276:
settings may revert to default values. Unwanted BIOS reset may be avoided by replacing the battery cell with the PSU power switch turned on and plugged into
573:
500:
423:
362:
413:
623:
325:
149:
222:
148:
MC146818 or similar) powered by a small battery when system and standby power is off. It is referred to as non-volatile memory or
160:
chipset and they may not be standalone chips on modern motherboards. In turn, the southbridge has been integrated into a single
382:
284:
motherboards, the PSU will supply 5V standby power to the motherboard to keep CMOS memory energized while the system is off.
442:
694:
261:
71:
596:
175:. For this reason, later BIOS implementations may use a small portion of BIOS flash ROM as NVRAM, to store setup data.
62:
141:
300:
232:
277:
608:
490:
352:
161:
157:
99:
331:
288:
153:
name CMOS memory comes from the technology used to make the memory, which is easier to say than NVRAM.
689:
38:
31:
91:
265:
579:
115:
316:
after a period of disuse, damaging components and traces on the circuit board near the battery.
631:
569:
496:
419:
358:
296:
119:
515:
561:
653:
313:
254:
247:
134:
464:
49:
264:
is unplugged or when the PSU power switch is turned off. This battery type, unlike the
207:
684:
678:
583:
287:
Some computer designs have used non-button cell batteries, such as the cylindrical "
292:
187:
669:
390:
648:
565:
236:
122:
664:
658:
597:
Ask a question » Replacing the battery of your motherboard (CMOS battery)
27:
Small, battery-backed memory component for storing a computer's BIOS settings
386:
257:
165:
156:
The CMOS RAM and the real-time clock have been integrated as a part of the
17:
145:
104:
213:
194:' design, the UEFI settings are still lost if the CMOS battery fails.
304:
269:
251:
527:
308:
228:
183:
98:
90:
30:"CMOS memory" redirects here. For other types of CMOS memory, see
273:
179:
172:
138:
126:
281:
260:. This cell battery has an estimated life of three years when
191:
164:. Alternatively BIOS settings may be stored in the computer's
43:
659:
How to replace dead CMOS battery and configure BIOS settings
186:
to store configuration data (NVRAM is a portion of the UEFI
37:"CMOS RAM" redirects here. For other types of CMOS RAM, see
516:
http://rom.by/files/AMIBIOS8-Flash-Recovery-Whitepaper.pdf
665:
Tutorial: How to replace the CMOS battery in your laptop
235:
barrel battery that has leaked onto the mainboard of a
67:
171:
The chipset built-in NVRAM capacity is typically 256
383:"What is CMOS? (CMOS & CMOS Battery Definition)"
443:"Intel 100 Series Chipset Family PCH Datasheet"
139:complementary metal–oxide–semiconductor (CMOS)
8:
376:
374:
437:
435:
246:The memory battery (aka motherboard, CMOS,
216:button cell, the most common CMOS battery
303:(Ni–Cd) CMOS battery that looks like a "
654:CMOS memory map (for Bochs PC emulator)
649:Definition of CMOS & CMOS Batteries
343:
95:NEC D4364G 8192 x 8 Bit Static CMOS RAM
250:(RTC), clock battery) is generally a
552:Yao, Jiewen; Zimmer, Vincent (2020).
129:settings. It is traditionally called
7:
326:Extended System Configuration Data
25:
61:to comply with Knowledge (XXG)'s
554:"Firmware Resiliency: Detection"
221:
206:
48:
670:How to replace the CMOS battery
609:"CMOS Battery on the Intel NUC"
1:
624:"Amiga 2000 Emergency Repair"
622:Williams, Al (July 8, 2018).
566:10.1007/978-1-4842-6106-4_4
492:Upgrading and Repairing PCS
465:"82430FX PCISET Data Sheet"
415:Upgrading and Repairing PCS
354:Upgrading and Repairing PCS
239:and damaged legs and traces
711:
36:
29:
528:"UEFI NVRAM - OSDev Wiki"
611:. Intel. 24 August 2020.
558:Building Secure Firmware
74:may contain suggestions.
59:may need to be rewritten
489:Mueller, Scott (2004).
412:Mueller, Scott (2003).
351:Mueller, Scott (2004).
278:an electric wall socket
262:power supply unit (PSU)
162:Platform Controller Hub
112:Nonvolatile BIOS memory
295:as well as some older
133:RAM because it uses a
125:that is used to store
108:
96:
332:List of battery types
102:
94:
560:. pp. 115–162.
445:. Intel. August 2015
39:Random-access memory
32:Semiconductor memory
695:Non-volatile memory
266:lithium-ion battery
314:leak devastatingly
297:IBM PC compatibles
190:ROM), but by many
114:refers to a small
109:
103:CMOS battery in a
97:
575:978-1-4842-6105-7
502:978-0-7897-2974-3
425:978-0-7897-2745-9
364:978-0-7897-2974-3
182:motherboards use
89:
88:
63:quality standards
16:(Redirected from
702:
636:
635:
634:on July 8, 2018.
630:. Archived from
619:
613:
612:
605:
599:
594:
588:
587:
549:
543:
542:
540:
538:
524:
518:
513:
507:
506:
486:
480:
479:
477:
475:
469:
461:
455:
454:
452:
450:
439:
430:
429:
409:
403:
402:
400:
398:
393:on 9 August 2016
389:. Archived from
378:
369:
368:
348:
225:
210:
84:
81:
75:
52:
44:
21:
710:
709:
705:
704:
703:
701:
700:
699:
675:
674:
645:
640:
639:
621:
620:
616:
607:
606:
602:
595:
591:
576:
551:
550:
546:
536:
534:
526:
525:
521:
514:
510:
503:
488:
487:
483:
473:
471:
467:
463:
462:
458:
448:
446:
441:
440:
433:
426:
411:
410:
406:
396:
394:
380:
379:
372:
365:
350:
349:
345:
340:
322:
248:real-time clock
244:
243:
242:
241:
240:
226:
218:
217:
211:
200:
85:
79:
76:
66:
53:
42:
35:
28:
23:
22:
15:
12:
11:
5:
708:
706:
698:
697:
692:
687:
677:
676:
673:
672:
667:
662:
656:
651:
644:
643:External links
641:
638:
637:
614:
600:
589:
574:
544:
532:wiki.osdev.org
519:
508:
501:
481:
456:
431:
424:
404:
370:
363:
342:
341:
339:
336:
335:
334:
329:
321:
318:
301:nickel–cadmium
299:, or a 3-cell
291:" used in the
231:-manufactured
227:
220:
219:
212:
205:
204:
203:
202:
201:
199:
196:
87:
86:
56:
54:
47:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
707:
696:
693:
691:
688:
686:
683:
682:
680:
671:
668:
666:
663:
660:
657:
655:
652:
650:
647:
646:
642:
633:
629:
625:
618:
615:
610:
604:
601:
598:
593:
590:
585:
581:
577:
571:
567:
563:
559:
555:
548:
545:
533:
529:
523:
520:
517:
512:
509:
504:
498:
494:
493:
485:
482:
466:
460:
457:
444:
438:
436:
432:
427:
421:
417:
416:
408:
405:
392:
388:
384:
381:Fisher, Tim.
377:
375:
371:
366:
360:
356:
355:
347:
344:
337:
333:
330:
327:
324:
323:
319:
317:
315:
310:
307:" (common in
306:
302:
298:
294:
290:
285:
283:
279:
275:
271:
267:
263:
259:
256:
253:
249:
238:
234:
230:
224:
215:
209:
197:
195:
193:
189:
185:
181:
176:
174:
169:
167:
163:
159:
154:
151:
147:
144:(such as the
143:
140:
136:
132:
128:
124:
121:
117:
113:
106:
101:
93:
83:
73:
69:
64:
60:
57:This article
55:
51:
46:
45:
40:
33:
19:
632:the original
627:
617:
603:
592:
557:
547:
537:11 September
535:. Retrieved
531:
522:
511:
491:
484:
472:. Retrieved
459:
447:. Retrieved
414:
407:
395:. Retrieved
391:the original
353:
346:
293:Power Mac G4
286:
245:
198:CMOS battery
177:
170:
155:
137:, low-power
130:
123:motherboards
111:
110:
77:
68:You can help
58:
690:Motherboard
397:2 September
237:synthesizer
158:southbridge
107:motherboard
679:Categories
474:23 January
338:References
18:CMOS setup
584:242541772
387:About.com
258:coin cell
166:Super I/O
72:talk page
661:(video).
628:Hackaday
449:16 April
320:See also
178:Today's
146:Motorola
135:volatile
105:Pico ITX
80:May 2021
495:. Que.
470:. Intel
418:. Que.
357:. Que.
255:lithium
214:CR-2032
582:
572:
499:
422:
361:
328:(ESCD)
305:barrel
289:1/2 AA
270:CR2016
252:CR2032
168:chip.
116:memory
70:. The
580:S2CID
468:(PDF)
309:Amiga
280:. On
233:Ni–Cd
229:VARTA
188:flash
184:NVRAM
173:bytes
150:NVRAM
685:BIOS
570:ISBN
539:2020
497:ISBN
476:2023
451:2016
420:ISBN
399:2015
359:ISBN
274:BIOS
192:OEMs
180:UEFI
142:SRAM
131:CMOS
127:BIOS
562:doi
282:ATX
118:on
681::
626:.
578:.
568:.
556:.
530:.
434:^
385:.
373:^
120:PC
586:.
564::
541:.
505:.
478:.
453:.
428:.
401:.
367:.
82:)
78:(
65:.
41:.
34:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
