# A computer problem
**URL:** https://boards.straightdope.com/t/a-computer-problem/192541
**Category:** Factual Questions
**Created:** [August 2, 2003, 1:48pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541 "2003-08-02T13:48:49Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@maleinblack](https://boards.straightdope.com/u/maleinblack)
#### Post date: [August 2, 2003, 1:48pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/1 "2003-08-02T13:48:49Z")
Hi there. I would like some valuble suggestions for my girlfriends screwed up computer.
The computer in question is a P4 2.0 Ghz pc with 256Mb of SDRAM.The motherboard used is a 845 chipset and has a 40GB HDD.The OS she is running is Win ME.
The pc was running fine until one day when there was a major power fluctuation while she was working on the machine.Since then it has been behaving strangely.We are able to boot up the pc(which it does properly) but once booted up the keyboard or mouse dont work.Even the BIOS setup cannot be accessed because the keyboard doesnt work.
I have checked out the connections and they seem to be mine.I even replaced the RAM to see if there was any problem with it, but the RAM had no apparent damage.
SO I would really appreciate if anyone can tell me how to go about solving this.Has anyone else experienced something like this?Is this a software problem or a potential hardare failure?
Thanx in advance guys.
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### Author:  [@Declan](https://boards.straightdope.com/u/Declan)
#### Post date: [August 2, 2003, 2:34pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/2 "2003-08-02T14:34:42Z")
> [@](#):
>
> \*Originally posted by maleinblack \*
> \*\*Hi there. I would like some valuble suggestions for my girlfriends screwed up computer.
> The computer in question is a P4 2.0 Ghz pc with 256Mb of SDRAM.The motherboard used is a 845 chipset and has a 40GB HDD.The OS she is running is Win ME.
> The pc was running fine until one day when there was a major power fluctuation while she was working on the machine.Since then it has been behaving strangely.We are able to boot up the pc(which it does properly) but once booted up the keyboard or mouse dont work.Even the BIOS setup cannot be accessed because the keyboard doesnt work.
> I have checked out the connections and they seem to be mine.I even replaced the RAM to see if there was any problem with it, but the RAM had no apparent damage.
> SO I would really appreciate if anyone can tell me how to go about solving this.Has anyone else experienced something like this?Is this a software problem or a potential hardare failure?
> Thanx in advance guys. \*\*
Sounds like the power supply went . The good news is its not that expensive to replace.
Declan
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### Author:  [@ForumBot](https://boards.straightdope.com/u/ForumBot)
#### Post date: [August 2, 2003, 2:38pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/3 "2003-08-02T14:38:10Z")
I’ll second what Declan said.
You should be fine with a 300, or maybe even a 350W power supply with that setup. Ask the people at the tech store what wattage they think you should need.
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### Author:  [@Number](https://boards.straightdope.com/u/Number)
#### Post date: [August 2, 2003, 3:38pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/4 "2003-08-02T15:38:07Z")
It doesn’t sound like a bad power supply since the machine boots and doesn’t shut off unexpectedly. A motherboard problem is much more likely. You should try swapping keyboards and mice, but if that doesn’t work then the PS/2 ports are probably fried. The only good solution then is a new motherboard. Check to see if it’s still under manufacturer warranty.
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### Author:  [@handy](https://boards.straightdope.com/u/handy)
#### Post date: [August 2, 2003, 3:42pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/5 "2003-08-02T15:42:17Z")
If it boots up fine, why would it be the power supply? Moke like the keyboard bios chip is cooked. I have seen it before.
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### Author:  [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)
#### Post date: [August 2, 2003, 3:44pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/6 "2003-08-02T15:44:21Z")
Yes, it’s definitely not the power supply. Keyboards and mice run off the +5 V bus, and since nearly all the logic on the mainboard and peripherals runs from it, and the processor core voltage is derived from it as well, it’s a safe bet the supply is fine. It’s possible, but unlikely, that both the keyboard and mouse were damaged during the power fluctuation, but more likely, it’s the PS/2 bus on the mainboard that went. Try **Number** ’s suggestion of swapping them out first, just to be sure. If everything else is working, instead of replacing the mainboard, consider purchasing a USB keyboard and mouse, if finances are a constraint.
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### Author:  [@maleinblack](https://boards.straightdope.com/u/maleinblack)
#### Post date: [August 2, 2003, 3:56pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/7 "2003-08-02T15:56:42Z")
Thanks for all the informative and prompt replies.
Actually **Declan** and **ForumBot** it seems to me that the power supply is fine because the computer boots up normally and does not shut down unless manually done.
**Number** and **Q.E.D.** I have already swapped the mouse with a working one (mine) but to no avail.Her mouse is an optical one and the light at the bottom lights up when the machine is booted.So would this happen even if the PS/2 ports are fried?
I am trying to arrange for either a mouse or a keyboard with USB which should clear up the picture a bit.
**handy** is it possible to repair/replace the keyboard bios chip?Or are we better of buying a new mobo?
I hope that we wont have to invest in a new mobo cause the current one just went out of warranty 15 days ago.:mad:
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### Author:  [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)
#### Post date: [August 2, 2003, 5:19pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/8 "2003-08-02T17:19:28Z")
Most motherboards have a fuse to protect the keyboard/mouse controller. Look near the connectors. The tricky part is that it’s often a picofuse, which looks more like a resistor than a fuse and requires some soldering to replace it.
If the fuse isn’t shot, then it’s more likely the keyboard controller. Those haven’t been a user replacable part since the days of the 386.
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### Author:  [@Alereon](https://boards.straightdope.com/u/Alereon)
#### Post date: [August 2, 2003, 5:30pm UTC](https://boards.straightdope.com/t/a-computer-problem/192541/9 "2003-08-02T17:30:16Z")
Yeah, I agree it’s the motherboard. Replace it, and invest in a good surge protector (not the $20 ones!).