Installed Antec Kuhler 620, Now Comp. Won't Post

Installation of Antec Kuhler 620 went without a hitch (or so I thought). A little jimmying to get the back plate on the back of the mobo, but everything else went smoothly.

Went to boot it back beep, no post, no video (monitor stays in sleep mode), NO BOOT at all.

I removed the cooler and the CPU. Re-seated the CPU and the cooler. Also re-seated the RAM and vid card and checked their respective power plugs for good measure. Still no beep, no post, and NOW the power shuts off 3-5 seconds after I push the power button. So, it seems worse than before -- previously the fans, etc. kept running until I turned the machine off.

Not sure what's wrong at this point. Help?


Win XP SP3
Intel Core i5-760 2.8 GHz 1156 Quad-core
Gigabyte GA-H55-USB3 LGA 1156 Intel H55 HDMI USB 3.0 ATX Motherboard
8GB Mushkin (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333
EVGA SuperClocked 01G-P3-1367-TR GeForce GTX 460 SE (Fermi) 1GB 256-bit GDDR5
11 answers Last reply
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  1. Where did you plug in the fan?

    What about the thermal paste? too much? too little?

    You need to just treat this like a new build failure to post. Something happened during the process that you didn't notice or that you don't now recall.
  2. Proximon said:
    Where did you plug in the fan?

    What about the thermal paste? too much? too little?

    You need to just treat this like a new build failure to post. Something happened during the process that you didn't notice or that you don't now recall.

    Fan is plugged into upper left of mobo where the previous stock cooler was plugged. Moved the stock case fan to the top of the case, too, but that power plug is the same.

    I used the thermal paste that was pre-applied with the new cooler.
  3. Go through the linked checklist fully then let me know. :)
  4. 1 through 23 completed. All the items below that I did not do. What exactly does re-setting the CMOS do?

    Also, I'm concerned that I may have tightened the CPU cooler too much, although I didn't wrench it down too much (or so I thought). Would that be a possibility?
  5. Probably not on the CPU cooler tightening... If you used a Phillips screw driver and put your muscle into it, perhaps. Generally on those types of screws you want to have them about as tight as you can get with just your fingers on the screwdriver, but not your fist. Well, that would be my personal rule but then I'm a somewhat arthritic 51-year old guy.

    We're talking about a 1/4 or 1/2 turn from completely tight in other words, and of course you would not do it one screw at a time, but rotate or X-pattern tighten through a couple-three rounds.

    Not all CPU cooler backplates are compatible with all boards. does the backplate contact something it should not?
  6. Well, the backplate is made of rubber, so it doesn't appear to be causing any harm.

    Good, it doesn't seem like I mashed my CPU after all, then. I made sure to not over-tighten it.

    Still.....any ideas on what the problem might be?
  7. Make sure the CPU cooler fan is actually working. A failed one might cause the system to not post. You could just test this by plugging a different fan into the board. If the system starts to post properly just shut it off as you then know what the problem is.

    That's the only thing that has changed, so it's where I would start.

    Beyond that you might need to get a motherboard speaker to see if there are any clues there.
  8. Put the old CPU fan in there, it's spinning alright, but no post.

    The replacement was as well, though, but it was definitely worth a try.
  9. OK. It is time start breadboarding and build and test the system in stages.

    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.

    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 (standby power supply): 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.

    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.
  10. Well, I know it's not the CPU, now -- RMA'd it, the new one won't boot either. Time to RMA the mobo....
  11. RMA'd the mobo, just go it back.

    Breadboarded it with the stock CPU cooler, posted fine. Loaded the liquid CPU cooler up and installed mobo, posts and boots to Windows fine now. Seems to be working ok.

    Thanks everyone for the help.
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