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Is it the MOBO or the CPU? Computer will not start.

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January 12, 2012 12:34:37 AM

Specs:

i5-2500k
Asus Maximus IV Gene-Z LGA 1155
Cooler Master Hyper 212 Plus
G.Skill Sniper Series (2x4GB)
RAIDMAX SMILODON ATX-612WBP ATX Mid Tower Foldout MB Computer Case With 500W Power Supply


I built everything as it should be. Power button and the front case LED blinks once, and the PSU fan moves slightly (maybe half of a rotation). I figure something may be connected incorrectly or the mobo may be shorting, so I remove it from my case and place it on a piece of cardboard. Remove everything except one stick of RAM in the second slot. Connect 8 pin and 24 pin power connectors. CPU in, heatsink on. Connect the power button cable from the case, power on... Same problem, however now the PSU fan spins for a good second, as well as the CPU fan. A green light flashes on the motherboard for about a second, then turns off. This sequence does not loop.

I've reset the BIOS and shorted the CMOS, paperclip-tested the PSU, tried every different configuration of RAM, inspected and re-seated the CPU, and so forth. I really haven't the foggiest what else could make this problem.

So it seems that it has to either be the MOBO or the CPU, neither of which is showing any signs of physical damage. I don't want to have to return BOTH to newegg. I don't have any old mobos or CPUs which I can swap in order to conduct a process of elimination (my current rig is a 6 year old XPS laptop).

My question is if there is a way to test these parts so I know which needs to be returned (or if there is something else I might have overlooked). If I took this into GeekSquad and BestBuy, do they have the kit to help me out?

Thanks for all you help!
January 12, 2012 1:33:54 AM

Most computer repair places cost 40 - 90 an hour to fix stuff, but they do usually have all the tools necessary to diagnose whatever the problem is.

Without knowing more about your computer my bet would be on a bad PSU.

What is the video card in the computer?
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January 12, 2012 5:50:02 AM

CPUs are really resilient to the point where 99% of the times it is mobo.
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January 13, 2012 1:25:45 AM

@Raiddinn: Having conducted the "paper-clip" test, and from reading other threads posted by others having a similar problem, I am confident that it is not the PSU.

I will talk to Geek Squad or similar and see what they will cost, but it looks like I will simply return the Mobo for replacement and hope for best, UNLESS someone else has a better suggestion?
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January 13, 2012 1:50:32 AM

Do I understand correctly that you
1) used a paperclip to turn on the PSU when it wasn't connected to anything
2) that it turned itself on successfully this way, and
3) that you drew the conclusion that the PSU was fine to power your system after this test?

Before you send everything back, you may want to try connecting the PSU to the motherboard and getting a flat screw driver and touching it to the two pins on the motherboard listed as PWR_BTN in the manual, preferably out of the case in the breadboarding environment.

This will do the completely usual thing of making it turn on and back off again.

The thing to do different here is every time it shuts down, immediately touch it again on those pins to force it to try to start again. Do it over and over again, like 30 to 50 times if you have to. It should still only take 2 or 3 minutes if the PC shuts off after 1 sec every time.

I have seen cases where if you keep trying to start it like this over and over again immediately after it shuts down that it will eventually turn on and stay on.

If it does eventually turn on and stay on, I can tell you immediately what the problem is.

BTW, do you have other things connected that aren't listed, like video cards?
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January 13, 2012 12:19:04 PM

I will try that.

And at present I do not have a video card. The only things connected were:
-CPU
-CPU cooler
-PSU
-1 stick RAM
-Mobo
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January 13, 2012 1:51:46 PM

@Raiddinn: So I tried what you suggested. It took more like 5 mins to get it to "try and start" again. I did this 3 or 4 times but it never turned on and stayed on.

The mobo has a built in on-off button. I tried using that instead of using the screwdriver-pin method, and I got it to attempt to turn on much more frequently (every 20seconds or so) but it would still not turn on and stay on.
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January 13, 2012 4:33:35 PM

Try taking all the RAM out and try to start it and tell me what happens.
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January 13, 2012 5:08:07 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.
http://www.tomshardware.com/forum/261145-31-read-postin...

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. Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. At this point, if you do not have a system (internal case) speaker, you really need one.


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, LED's, or fan activity:

Check for line power at the PSU input. Extension cords, power strips, and power cords do fail.

If you have power and no beeps, suspect components in likely order are PSU, motherboard, and CPU.

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 13, 2012 8:07:05 PM


@JSC:

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

Before I go through all the steps you outlined above, I noticed this line. The CPU sits in an LGA1155 socket, there are no "cables" dedicated to it's power supply that I know of. Am I missing something really basic here? Or where you referring tot he ATX 20+4 pin power supplies connected to the mother board?
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January 13, 2012 8:16:01 PM

There is a 4 or 8 pin connector close to the CPU. That is the CPU power connector that he is talking about.
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January 13, 2012 10:47:05 PM

So just an update. The 4-pin 12V which I was using for CPU power was one which came very closely entwined with the 20-pin ATX connector. I looked at all the other connectors (they are plenty) and noticed that there were two other 4-pins and a single 6 pin. I decided I would try one of the other 4-pins, this one with only yellow and black wires (the one I was using previously had yellow, black AND red wires) and wouldn't you know, it started up! Hurray!

My girlfriend was so proud of me (or sick of me tinkering with my computer) that she decided to have sex with me, and now we have to go out, so I can't continue on and see if it is really working now.

Of note, despite having the case speakers connected, there was no "beeps" at all. Also, the mother board LED status lights read code "34" which translates to "post memory initialization". I don't know if this is an error or if it is just indicating a certain step that the system is going through. I will have to determine that later when I actually hook the thing up to a monitor.

Also, in case I wasn't clear earlier, I do not have a GPU nor do I intend to purchase one just yet. For now, all I will be using the graphics capability of the Sandy Bridge until I'm done spending half my days playing Skyrim on Xbox, and begin feeling the need to play game on my computer again.

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January 13, 2012 11:24:29 PM

If you shove in a 560 TI or something you could have 10x the performance of your XBOX on Skyrim. Just FYI.

Guess it makes sense why the computer was having difficulty starting then.

You say that you used the 4 pin out of the 20 + 4 adapter with 20 in the motherboard and 4 in the CPU power slot?

Did you have 4 unused ones in the other motherboard slot?

Anyway, do the RAM tests that it says in JSCs guide. Try it with just one stick and see if it boots. Try taking the battery out for 30 min to make sure there isn't anything corrupted in the configuration from the past stuff that was going on if necessary.
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January 14, 2012 2:52:04 AM

@Raiddinn

The mobo power had 24 slots, to which I attached a 20pin connector from the PSU.

The CPU power had 8 slots, 4 of which were covered by a plastic cap, to which I connect one of the 3 available 4 pin connectors from the PSU.

And yes a 560 would give me great performance on Skyrim, but I'm pretty happy with what XBOX is giving me right now. I have a pretty low threshold for what I consider "great graphics". Once you cross over that line I don't care just how far you go, because it's good enough... plus I'm more looking into getting a 460 a short way down the road.
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Best solution

January 14, 2012 12:42:38 PM

in the computer, does the PSU sticker say RX-500S or RX-500AF or some other part number?

The 20+4 should go in the 24 slot and there should be a 4+4 that occupies the whole 8 slots. Ideally, none of these ports will go unoccupied.

Put the 20+4 in the 24 port and see if you can manage to fit both of the other two into the 8 slot at the same time. Both the clips should probably be touching each other most likely.

The ones that go in the 8 port should be keyed. There should be one with two square pins diagonally across from each other (left) and the other should have 4 round ones (right).
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January 14, 2012 4:03:30 PM

Wow I'm an idiot..

Ok I'll do all that, put it all together, and see if the Boots. I'll keep you updated...
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January 15, 2012 6:37:33 PM

Ok, so problem solved.

It turns out I am, in fact, a complete amateur. I had only 20 pins in the 24 pin socket, because I thought that they gave you extra sockets in case you had psu with only 24 pins, when in fact it is the other way around.

I'm still not 100% sure on the CPU power though. There are 8 sockets for the the CPU power, but 4 of them had a little cap covering them. I connect two of the 4-pin power connectors from the PSU, popped that cap off and plugged 'em in. Hope I was suppose to do that.

Anyway, as of right now I am writing from my new rig. I'm not sure who to give credit to. JSC for making me think about the power connections or Raiddinn for get it exactly right. Thank you to you both!
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January 15, 2012 6:37:57 PM

Best answer selected by erasmus22.
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