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Will PC post without CPU or Damaged CPU?

VulcanX

Member
Apr 15, 2008
194
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0
What will happen if no cpu is present? will the post give wierd sequence of beeps or nothing? and if your cpu was maybe damaged in a lightning storm, will it cause the mobo to not post even if their is power to it?
I had a strange one where i tried 2 seperate cpus in a mobo and it just didnt wana kick at all,that same dude then got another board and same story, and i tried my own LGA775 in there, and still nothing, but that LGA of mine which was actually fried in a lightning storm, but how do i determine if its the CPU or mobo gone? i dont have spare parts as such
 

Nathelion

Senior member
Jan 30, 2006
697
1
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Swapping in other parts is the only way to test it that I know of. Unless you have something dead obvious, like a bulging capacitor.
 

Denithor

Diamond Member
Apr 11, 2004
6,300
23
81
Does the motherboard have any lights indicating that it's at least getting power distributed around? Many do, some don't.

Otherwise I don't really know, I do have a spare motherboard at home I can test tonight to see if it will boot or do anything at all without a cpu. I'll post back this evening to let you know.

EDIT: Another idea from this thread is to try a new battery in the motherboard.
 

degibson

Golden Member
Mar 21, 2008
1,389
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I'm not aware of any desktop-class machines that don't rely on their primary CPUs to boot. My guess is no, it won't even try to POST (I don't think it can).
 

zsdersw

Lifer
Oct 29, 2003
10,560
1
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No, the motherboard won't POST without a CPU in the socket. I've never seen one do that.

I also believe it won't post without any memory.
 

Ratman6161

Senior member
Mar 21, 2008
616
75
91
Originally posted by: zsdersw
No, the motherboard won't POST without a CPU in the socket. I've never seen one do that.

I also believe it won't post without any memory.
Also will not post without a video card installed or an onboard present.
 

alfa147x

Lifer
Jul 14, 2005
29,844
24
81
Originally posted by: degibson
I'm not aware of any desktop-class machines that don't rely on their primary CPUs to boot. My guess is no, it won't even try to POST (I don't think it can).
so there are some workstation class boards that can?
 
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Foxery

Golden Member
Jan 24, 2008
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Originally posted by: alfa147x
Originally posted by: degibson
I'm not aware of any desktop-class machines that don't rely on their primary CPUs to boot. My guess is no, it won't even try to POST (I don't think it can).
so there are some workstation class boards that can?
He didn't say that. It's unlikely that much of any type of motherboard can do anything but beep without a CPU. At best, some fancy ones have an LED display that will show you an error code.

Come to think of it, part of a POST is detecting the CPU. Without one, it won't go any farther, and since this is one of the first steps, you shouldn't see anything on the screen.
 

Pelu

Golden Member
Mar 3, 2008
1,208
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to get post you need 3 things inside the computer besides the mobo and PSU... and is one cpu... one memory.. and one video card...
 

VulcanX

Member
Apr 15, 2008
194
0
0
what if you take the keyboard out? doesnt that also cause it not to post? bcoz the keyboard is essential for operations on a pc?
 

Diogenes2

Platinum Member
Jul 26, 2001
2,151
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There is sometimes a BIOS setting that says something like " Stop On All Errors Except Keyboard " --
But no - a missing keyboard will not keep any PC I know of, from booting - Windows machines will boot all the way to the desk top ...
 

zsdersw

Lifer
Oct 29, 2003
10,560
1
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Originally posted by: VulcanX
what if you take the keyboard out? doesnt that also cause it not to post? bcoz the keyboard is essential for operations on a pc?
It will POST, and usually say something like "Keyboard error".

The three essential hardware components for POST are CPU, RAM, and video (either integrated or a separate card).
 
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ch33zw1z

Lifer
Nov 4, 2004
32,910
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Just to clarify what people are typing here. When you refer to POST, it means Power on Self Test. Yes, the three essential components for a CLEAN post are CPU, RAM, VGA. If these are installed, and the system board sees them as good then you will receive ONE beep after POST is complete. If any of the three components are missing, you receive POST errors indicated by a series of beeps. These POST error beep codes vary depending on the BIOS manufacturers programming.

If you remove all three of these and still do not receive POST error beeps, then there's something wrong with the system board, uninstalling/reinstalling might clear it up. It will not damage the system board to attempt to power up without the three essential components, but it might damage the system board if you have a bad components installed when you start it up.
 

skyking

Lifer
Nov 21, 2001
19,558
1,318
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Originally posted by: zsdersw
Originally posted by: VulcanX
what if you take the keyboard out? doesnt that also cause it not to post? bcoz the keyboard is essential for operations on a pc?
It will POST, and usually say something like "Keyboard error".

The three essential hardware components for POST are CPU, RAM, and video (either integrated or a separate card).
Someone has the quote,
"keyboard error or missing keyboard. Press any key to continue" :laugh:
 
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JesseKnows

Golden Member
Jul 7, 2000
1,980
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POST requires the CPU. Perhaps some special mobos can do something w/o CPU, I've never seen that. No CPU = no sound, no video. You could get the power LED on and the fan on (and maybe a click when the speaker gets a DC spike), that's it.

With CPU and no memory, typically you get a beep code. Ditto with CPU/memory and no video. I've observed both many times.
 

shortylickens

No Lifer
Jul 15, 2003
78,804
11,774
126
Originally posted by: JesseKnows
POST requires the CPU. Perhaps some special mobos can do something w/o CPU, I've never seen that. No CPU = no sound, no video. You could get the power LED on and the fan on (and maybe a click when the speaker gets a DC spike), that's it.

With CPU and no memory, typically you get a beep code. Ditto with CPU/memory and no video. I've observed both many times.
I have a DFI NF4 Ultra SLI DR Expert. Without CPU or RAM you still get a number of beeps and lit LED's on the board. It can help troubleshooting if I bother to read the manual. No display though.

Without video I dont know what the thing does. It could boot up all the way into the O/S for all I know.
It does give me a few beeps and lights, again thats good for troubleshooting.
 

Zap

Elite Member
Oct 13, 1999
22,377
2
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Originally posted by: shortylickens
I have a DFI NF4 Ultra SLI DR Expert. Without CPU or RAM you still get a number of beeps and lit LED's on the board. It can help troubleshooting
Sounds as if the board has an onboard POST card. Some boards have status LEDs (I know some Biostar Tforce boards have a set of four LEDs) and some boards actually have a numeric display.
 

aigomorla

Cases and Cooling Mod PC Gaming Mod Elite Member
Super Moderator
Sep 28, 2005
18,754
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Originally posted by: zsdersw
No, the motherboard won't POST without a CPU in the socket. I've never seen one do that.

I also believe it won't post without any memory.
it wont post if there is no :

1. cpu
2. Ram
3. Those without igp videocard.

Beep codes are specific to motherboard company. :T

DOE Cheez beat me to it. Should of finished reading the entire post. :T
 

hmazuji

Junior Member
Oct 14, 2017
1
0
36
this thread is coming up on 15 years old
are new motherboards (2021) able to post without a cpu or ram
 

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