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Replace CPU or Mobo ??

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January 21, 2011 11:18:50 AM

The older used parts:
Gigabyte GA-M55SLI-S4 Motherboard
AMD Athlon X2 6000+ 3.0Ghz processor
Asus Triton 78 CPU Cooler
G.Skill 2x 1GB Ram DDR2 PC26400 800mhz
AData 2x 1GB Ram DDR2 PC25300 667mhz
Asus nVidia 9800GT 512mb Graphics card
Pioneer DVR-111 DVD/CD burner
Cooler Master Elite 330 case
2x Seagate 320GB SATA HDD

The new parts:
Western Digital 500GB SATA HDD
Thermaltake Litepower 600w PSU
Acer 23" LCD screen

*Using Artic Silver 5 thermal paste
Anti Static wrist band


I have tried reading other peoples similar problem but I need advice.I got a older system and am adding newer parts in it for my brother.
I have previously used it and it was all working fine no problems but it has been disassembled and out of action for a good year or two...

Everything was rebuilt, all connected properly etc. (I have built a fair few systems).

OK the thing is during boot up the BIOS screen does load up, then immediately the whole computer powers off...
The BIOS screen starts to detect IDE drives then everything dies, as more times I have tried it just dies straight away before without seeing the BIOS screen now.

I have tried all kinds of tests no joke, removing everything all components trying components individually, listening to the POST beeps they were correct and what not.
I have taken it out assembled again, tried without the front panel headers and turning it on by touching the 2 power pins.
I have the 4 pin ATX, 20+4 pin ATX and a molex plug (the mobo has extra power for the gfx card) into the motherboard tried all those combinations, all fans spin up, I can hear the HDD's power up also, so its not the PSU + its new.

Also I have all the components out now on cardboard at the moment, so shorting is not the issue with the case.
I have tried another crappy AMD Sempron CPU and still the same problem of powering off, but it does show the BIOS screen instead of immediately killing itself (so its lasts slightly longer).

So I have just given up and asking for help and my verdict is its either the CPU or Mobo has had its time and needs to be replaced !! I believe it may be the motherboard at this point.
But preferably instead of buying both to replace (if I dont have to), is there a method to suggest to narrow it down to be more specific...

More about : replace cpu mobo

January 21, 2011 11:34:38 AM

Did you try w/out the HDD connected?

Symptoms sound like a bad PSU to me. Do you have another one to try? New? Stuff like this can either be bad out of the box, fail when new or last a long time before dieing of old age.

Good luck!
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January 21, 2011 11:54:21 AM

Yes have tried with no SATA and power to the Hard drives and just testing with one plugged in.
I could test with my PSU in my main rig.
Also that new PSU would have sufficient wattage for that system and everything does power up, when I have just CPU, RAM and Graphics card plugged in the power is constant with just the beep from probably the CPU overheating without the heatsink in proper place.
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January 21, 2011 12:23:39 PM

OK - PSU stays up with a limited load and goes down when you add the drives? That really does sound like a PSU that can't support the entire load. You should be able to disconnect drives, connect a monitor and keyboard and at least look at the BIOS screen. It might even have voltage monitors that might tell you more.

Do you have a CPU fan connected? Working? Do some of these refuse to work w/out that?
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January 21, 2011 12:34:18 PM

I havent tried all 3 HDD's outside the case on the cardboard yet. It did no difference when I had all 3 running and span up in the case though.

I got 1 HDD plugged in atm (on cardboard), also the CPU cooler (fan) is working and the mobo works booted without CPU fan plugged in.

The POST beeping is constant now though, so CPU might be the problem maybe...
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Best solution

a c 122 B Homebuilt system
January 22, 2011 12:42:29 PM

Restart from the beginning.

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.

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.
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January 29, 2011 12:38:17 AM

Thanks to HankB99 and jsc. Very helpful and the troubleshooting thread is pretty intense.

My conclusion was the new PSU is faulty.
I took apart my computer and tried it with other computer and it was working fine, I even installed Widows 7 and some programs.
To make sure I plugged the new PSU back in and it immediately powered off again.

So Ive sent it vack into the shop where I bought it and apparently the techs cant find anything wrong with it at the moment (I get a $45 fine and have to pay postage again if there is no problem), I sent them basically what I wrote here and will see how we go.
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February 8, 2011 12:23:37 AM

Best answer selected by k1n23.
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