Start MoBo without CPU?

BoB3rt

BoB3rt

BoB3rt

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Is it possable to start up ya motherboard without the cpu in?

Will it load the bios still etc? or just power up and do nothing?

cheers
 
You know what, I'll second this question - I have no idea. Often wondered how you would know that your motherboard was the problem in a non-functioning PC.

I'm sure I'll feel stupid when someone explains the undoubtedly obvious answer mind you!
 
You know it's a problem if you stick a working CPU in and it doesnt work.

What exactly do you expect to happen if you try to boot up? If it doesnt have a processor then how is it supposed to do anything, let alone get as far as loading a BIOS?

Hence, I would imagine the answer is no :p it'll power up and do nothing (which is incidentally what generally happens when a cpu/mobo fails)
 
It will power up and do nothing.

I tried it to get some photos taken when i had no CPU and no monitor attached.

The mobo lights come on, fans spin up etc..
 
Alex74 said:
You know it's a problem if you stick a working CPU in and it doesnt work.
Click to expand...

So if I was to change my Intel CPU, and bought an AM3 board and CPU and they didn't boot, how would I know which was faulty?

For instance, would I get an POST error stating that there was a CPU error?

Always wondered this!!
 
I do have reason for asking this, as i have a on going problem with start ups.

Although i can not tell if it is the CPU or motherboard.

after serveral retries it will eventually boot it tends to start and do nothing.
(fans start, HDDs start, GFX card fan starts, CPU fan 100%, no signal to monitor)

Tested all other hardware, so i know it is the CPU or Motherboard.

but if this is the case it could lean toward the CPU not being recognised or faulty... but could mean mobo is faulty AHHH!
am wanting to replace one or the other but might be easier to replace both!

thanks
 
jmp_78 said:
So if I was to change my Intel CPU, and bought an AM3 board and CPU and they didn't boot, how would I know which was faulty?

For instance, would I get an POST error stating that there was a CPU error?

Always wondered this!!
Click to expand...

Cpus with no visible damage to the underside/pins are rarely faulty. Beep codes would be another way to give you a better idea.

But to fully diagnose PC faults for sure, you tend to need to have two sets of parts. This is why there used to be more complaints in the old days about frequent manufacturer socket changes. These days we are just used to being shafted by socket changes.

Its another reason to make you stick to the same manufacturer when the socket doesnt change, though. Hence AM2 -> 2+ -> AM3.
 
JTrickle said:
Cpus with no visible damage to the underside/pins are rarely faulty. Beep codes would be another way to give you a better idea.

But to fully diagnose PC faults for sure, you tend to need to have two sets of parts. This is why there used to be more complaints in the old days about frequent manufacturer socket changes. These days we are just used to being shafted by socket changes.

Its another reason to make you stick to the same manufacturer when the socket doesnt change, though. Hence AM2 -> 2+ -> AM3.
Click to expand...

Nice answer - thanks :D
 
I've turned motherboards on before to see if I could get beeps etc without a CPU.

Sounded like Johnny 5 having an orgasm.
 
The bios POST test is simply a program stored on a flash chip on the motherboard, it needs a cpu to execute it just as any other program would. No cpu no POST end of story. I dont even think that a port 80 diagnostic card will work when no cpu is on the motherboard, as they still rely on the cpu to run the post test program.

My intel motherboard actually puts the port 80 diagnostic codes on screen during boot up. On a multicore processor, a fault on the primary core (core 0) can also cause failer to post.

Its actually pretty tough to tell if its motherboard or CPU related, but complete failer of a core is pretty rare, so in most cases where post fails, I would tend to blame the motherboard over a cpu.
 
BoB3rt said:
I do have reason for asking this, as i have a on going problem with start ups.

Although i can not tell if it is the CPU or motherboard.

after serveral retries it will eventually boot it tends to start and do nothing.
(fans start, HDDs start, GFX card fan starts, CPU fan 100%, no signal to monitor)

Tested all other hardware, so i know it is the CPU or Motherboard.

but if this is the case it could lean toward the CPU not being recognised or faulty... but could mean mobo is faulty AHHH!
am wanting to replace one or the other but might be easier to replace both!

thanks
Click to expand...

That may be a power issue had the same problem with my old setup with a hiperx psu changed it a more powerful psu corsair and never had any startup issues after that.
 
Working out which of a cpu and motherboard is dead is very tricky and can take a considerable length of time if it turns out that one dying killed the other in the process.

Here's my experience in determining which of cpu and motherboard was at fault, may be useful or just mildly interesting.
 
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I had to update my bios for an AM2 + board that was AM2+ ready but the bios was not, lucky to have an AM2 phenom in my brothers pc that I could use to update the bios
 
Out of curiosity, I once powered up an ASUS A7N something or other board without a CPU. I got a message on the monitor saying "No CPU Installed!" I was very surprised for the reasons posted above.
 
dazza13 said:
That may be a power issue had the same problem with my old setup with a hiperx psu changed it a more powerful psu corsair and never had any startup issues after that.
Click to expand...

I have already tried a diffrent PSU, plus i have a corsair 520HX which am guessing is more an enough to run my system... i have even ran it at barebones to check this.

so tricky to determin which is at fault, although having a nose over at ASUS a few ppl have the same problem with P5KC and a Q6600 could be bad compatability, because as i said: after several restarts it will boot up, and once in windows there are no problems.

thanks
 
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