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MSI Mobo turns on only when CPU power connector not plugged in??

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Louie26

Louie26

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May 4, 2010
As the title states, my MSI NF750 mobo only turns on if i unplug the 4 pin CPU power connector. It shut off on me the other day and now when i try to turn it back on the led's light up and fans spin for bout half a second then turns back off. At first i thought it was my psu cuz similar thing happened a while back and i just replaced the psu. But i took out the psu and put it in another system and it worked just fine. Then when i put it back in the F'd up system i forgot to plug in the 4 pin cpu connector and i pushed the power button and all the led's and fans started right up, but as soon as i try to power it on with the 4 pin cpu plugged in it wont start. Anybody have any ideas? Is my mobo shot? Or is it my cpu? and help greatly appreciated!! thanks!
 
That is weird how you got it working by screwing up :)

toss in a bit of analisis, what occurs when the fan is not spinning ?
the processor goes into thermal cripple mode , which would use less overall energy?

why do you have such trouble with PSU then buy lesser PSU item again ?
The first time a lesser PSU failed me, then another one shot sparks out the back after a year of use, and then another one that came free with a case croaked and smelt bad. . . . Oh wait a minute i never learned the first time either :) oh well.

i am not saying the PSU IS bad, but that is a possibility here that i can think of, it certannly is an approprite size for your system, and you did test it.

did you change to a DIfferent 4Pin fan item? and check the one you have plugged in, to see if IT itself might have some rare out of the blue short?
 
Does your motherboard have an 8 pin CPU power plug by any chance? If so maybe your putting the 4 pin into the wrong four. Though it should of come with a cover on 4 of th pins.
Also have you inspected the PSU wires for any physical damage from maybe getting pinched when closing your case?
 
Try taking the video card out and using the onboard video.

I'm curious. How do you get 5 gb of ram installed on a board that has 4 ram slots? That's rather odd. It would require that two of those sticks would be 512mb modules. Does anyone even make 512mb modules of DDR3 1333? I couldn't find any on NewEgg. What brand is this ram?
 
Last edited:
Yanko693 said:
Does your motherboard have an 8 pin CPU power plug by any chance?
Click to expand...

I thought the same thing but after looking it up there is only a 4 pin connector for the cpu on the board.

OP when you tried the power supply in another system did it have a 4 pin connector on the motherboard that you tried it on and did you have it connected up to that board? just curios if maybe they pinned out the 4 pin connector wrong and you didn't have to use it on the other board that you hooked it up to.
 
Last edited:
trents said:
Try taking the video card out and using the onboard video.

I'm curious. How do you get 5 gb of ram installed on a board that has 4 ram slots? That's rather odd. It would require that two of those sticks would be 512mb modules. Does anyone even make 512mb modules of DDR3 1333? I couldn't find any on NewEgg. What brand is this ram?
Click to expand...

1+1+1+2?
 
If the PSU wires & plug and the 4-pin plug on the board all look OK then I'd say it's time to pull the board out of the case and try it there. Offhand it sounds like the CPU power is either being grounded or has a bad connection somewhere.

But - it could be the CPU is seated badly, it could be something else is grounding out a little and the CPU pulls enough extra power to kick in the fault protection. There could be a lot of things causing that problem and for most of them the first step is taking the board out of the case and stripping down the system to bare essentials ...
 
TheQuadFather said:
1+1+1+2?
Click to expand...

You can do that but it wouldn't be running in dual channel mode.

QuietIce's suggestion is good. It wouldn't surprise me if there is a misplaced motherboard offset grounding out against the backside of the motherboard.
 
OK, so ive taken the board out and tried it with 1 stick of ram, gpu, and 1 hdd. same thing. i tried every stick of ram. same thing. i took off the gpu, same thing. i took off the hdd, same thing. tried it with just the mobo and cpu, same thing, led's flash for split second then back off. so i got frustrated and took out the cpu and unplugged the 4 pin and turned it on and while it was on i plugged in the 4 pin cpu plug and it sparked.... now i dont know if it sparked because i tried plugging it in while the mobo was on, or somethings wrong with the plug in or psu or idk... hmmm
 
oh and the 5 GBs of ram thing, i used to have 2+2+1, but i took out the 1 so im runnin 4GBs dual chan now
 
Never remove the power connections while the board is running....if it wasn't toast before it probably is now.
 
Trap05 said:
Never remove the power connections while the board is running....if it wasn't toast before it probably is now.
Click to expand...


i didnt remove it while it was running. i turned off the board unplugged the 4 pin, turned on the board, and in a fit of frustration plugged in the 4 pin. i know not the smartest thing to do, but eh....
 
Same difference if I was you I'd be ordering a new power supply (Rosewill is crap even if it does work) and a new motherboard.
 
ohh it was the CPU cable, not the CPU fan cable.

yes there could be a healthy spark when connecting it Live (even when nothing is wrong). IF there was burnouts on the motherboard regulation stuff it could be an even bigger spark, and the PSU should shut down.
in fact if the PSU does shut down then, i would suspect the motherboard regulations , the mosfets and regulators and capacitors, or if it was just put into a Metal case, a possible grounding or short.

now i would go with something wrong with the motherboard, even before you were harsh with it, And/Or the power suppy.
given enough time looking at the motherboard you might even see what the problem is. look right around the cpu for the parts there.
You probably didnt specifically lose anything, you had not already lost.

CGS Drone makes a good point, of checking the wireing , especially if your using modular power cables.
.
 
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If there are no signs of a short on the motherboard, the plug or the cables then you've eliminated everything that could be a problem except the board, CPU, and PSU. Unfortunately it could be any one of them and the only way to know is to R&R - remove and replace with a known good part ...
 
New to the forums here and a little late for this ? maybe, but I had the same problem with the MSI 880gma-e45. Both times it quit on me after doing stress testing (Prime 95) for about 1/2 hour at 3.08 GHz and the second time at 3.32 GHz. First time RMA'd the mobo. Just happened again today. I'd say it's the Mobos. Won't buy a MSI again!
 
jcamel24 said:
New to the forums here and a little late for this ? maybe, but I had the same problem with the MSI 880gma-e45. Both times it quit on me after doing stress testing (Prime 95) for about 1/2 hour at 3.08 GHz and the second time at 3.32 GHz. First time RMA'd the mobo. Just happened again today. I'd say it's the Mobos. Won't buy a MSI again!
Click to expand...

Ditto!!
 
I think he fixed it. This thread is old.

Please check dates before posting.
 
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