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CPU restart loop

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April 18, 2011 4:33:23 PM

Hello :) 

I recently bought a full build for the 5th or 6th time as I was making a PC for a friend, fairly cheap £300 total (in the past I have done full builds of £1500 and had no issues) so I get everything configured - and do a test outside the case.. something I always do as it can be fiddly if you have issues.

I start up the PC and after 4 or 5 seconds it turns itself up and then restarts - and just loops continuously.

I did the normal 'remove a component at a time and see what happens' after many different combos I found the only one where it happened was when the CPU was on the mobo, when everything but the CPU was there - there system started up and just idled (no post beeps though, unsure if I would even get any or not though)

I bought all my components from scan as I wanted them quickly, have used them quite a bit for the last 4-5 years so expected some good help when I queried them about it - I received an email around a week after I told them my issue and they simply told me to do what I had already done and informed them of doing, switch components around and see if one combo works etc. after mailing them back informing them that I did it (I did it again just for laughs, same thing happened) they then informed me I would need to get a hold of another CPU (what?) and reset the bios this way... personally Im pretty sure I dont have to do this - I've never had to buy a secondary component to test problems myself and doubt that is standard code of conduct for newly bought products :D 

The fan to the cpu is connected fine, this was pretty much the only problem I thought it could be - but it was not.

components:

CPU: Intel Dual Core Wolfdale E5800 - http://www.scan.co.uk/products/intel-pentium-dual-core-...
Mobo: MSI g41m-p25 Intel g41 s775 - http://www.scan.co.uk/products/msi-g41m-p25-intel-g41-s...

Before I get back to SCAN again, who have very surprisingly been very unhelpful so far, was just wondering if anyone has run into anything like this before and if it is anything other than a faulty mobo / cpu?

More about : cpu restart loop

April 18, 2011 6:02:17 PM

"I've never had to buy a secondary component to test problems myself and doubt that is standard code of conduct for newly bought products"

Hehe, no.... it's definitely standard code of conduct, because many products, ESPECIALLY motherboards can be "DOA" (Dead On Arrival).

So basically, you're saying that everything is fine (except it doesn't post) as long as the CPU is not in the motherboard? Hmm, well the motherboard you're using SUPPORTS the cpu you're using....so this is weird to me, though i don't have much experience with intel. Maybe the CPU is DOA?

PS: Is your cpu getting power? (Is the cpu power cord plugged into the motherboard?) Also..... I hope this isn't too obvious, but is the cpu placed properly int he mobo? A certain corner of the cpu has to meet up with a certain corner of the mobo...which you probably already know after putting together so many rigs.
April 18, 2011 10:51:41 PM

yes all is powered and so on, properly placed (pretty much impossible to not place a cpu right these days, only fits on way) even tried a diff PSU to see if it was anything to do with that, which it wasn't.

Ive never had any DOA gear so far, I think I have been quite lucky - seeing as though in the past I have bought £200-400 CPU and mobo from SCAN you think they would try to help me out over this current combo at £100 :D 
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April 18, 2011 10:57:41 PM

natoRious said:
yes all is powered and so on, properly placed (pretty much impossible to not place a cpu right these days, only fits on way) even tried a diff PSU to see if it was anything to do with that, which it wasn't.

Ive never had any DOA gear so far, I think I have been quite lucky - seeing as though in the past I have bought £200-400 CPU and mobo from SCAN you think they would try to help me out over this current combo at £100 :D 


Hehe :p  Yeah, to be honest i'm not sure what the issue is, either the motherboard cpu socket is shot, or the cpu itself is shot haha
a b à CPUs
April 19, 2011 12:47:48 AM

I would question either the motherboard or the power supply. Easy way to check power supply is to hook up a voltmeter and see what it pumps out. If the voltmeter dances around a bit then more than likely its bad, try the power supply on a different computer just to make sure. That leaves the mobo, in which I would just send it back...
a b à CPUs
April 19, 2011 12:52:08 AM

I'm sure there's another CPU or motherboard somewhere you can test those items with. If you were in the U.S., I'd send you an old 775 board I have at shipping cost.
April 19, 2011 8:13:57 AM

Thanks for the replies - hopefully I hear back from them as indeed I would just like to send it off and let them test it all out - I only had a backup PSU and thats all I could test, dont have any other 775 boards or cpus in the house :D  so no chance of a test there.

Again, thanks, =)
a c 172 à CPUs
April 19, 2011 12:05:22 PM

Work systematically through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
April 19, 2011 4:02:09 PM

Thanks for your great reply, I always 'breadboard' too, just makes things easier long term :) 

I tested with just mobo, cpu and two different PSU's and simply the system starts up, runs for maybe a few seconds - then turns off and a second later restarts and loops. I simply wanted to know if this was a common issue or if it was a simple fix - otherwise I will just send the problematic parts back to SCAN, as there should be no major issue from new products out of the box.
April 19, 2011 4:05:11 PM

one small question though, could this be caused by an old bios setting originally being on the board?

SCAN have come back to me but are asking me to pay £10 + VAT so they can 'flash my mainboard' :D  these guys should be doctors with this sort of pinpoint diagnosis
a b à CPUs
April 19, 2011 11:18:29 PM

It could be a bios setting/version, but seen as how you can't flash a bios without a post (shy of replacing bios chips), there's not a lot you can do. Obviously, you can remove the battery/set the reset CMOS jumper. But you've already attempted that.
April 20, 2011 12:01:36 AM

dalauder said:
It could be a bios setting/version, but seen as how you can't flash a bios without a post (shy of replacing bios chips), there's not a lot you can do. Obviously, you can remove the battery/set the reset CMOS jumper. But you've already attempted that.


yup indeed, and now they are asking me to pay them to fix the issue - I would understand (maybe) if this was a 6month old board or something - but straight out of the box? wow :) 
!