Is my South Bridge fried?

Ok guys. Any input will be greatly appreciated. PLease help me figure this out:

The computer is crashing. I have not managed a successful boot yet. If you get to the point of loading services in Windows - it crashes with the BSOD and instantly reboots so I can't even see what the error was. If it crashes in BIOS (prior to even booting) - it can do so at any point - while detecting drives, usb devices, or after.

Mobo is ASUS P5B.

Things I tried:

1. New PSU (Hiper)
2. different RAM
3. different Video Card.

4. Disconnecting the Hard drive. Now this is where it gets tricky. With no HDD connected, you can successfully boot off the cd and run windows setup. Even with HDD connected you can run windows setup but it crashes right when windows starts looking for a place to install itself.

5. using other SATA slots, even the JMicron one.

Other thoughts: if it crashes before booting the OS, it looks more like going into suspend mode: hdd powers down but all the fans are spinning, with or without video signal (no consistency here).

The keyboard does not react every other time I boot. So sometimes I can get into BIOS and sometimes not, and get the "no keyboard detected code).

So, that's why I suspect the South Bridge: It controls the USB ports and the SATA controllers.

What do I do? Buy a new mobo?
17 answers Last reply
More about south bridge fried
  1. Are you installing two sticks of RAM ? there's a possibilities it's a failed dual channel or bad RAM. Try with only one stick of RAM.

    Go to BIOS, disable any peripherals you don't need such parallel or serial, usb, LAN, AHCI or NCQ (if any).

    Does the temperatures are in good range ?
  2. I did try the single stick indeed. Still crashing, and doesn't explain the keyboard (usb port) problem.

    All the unused peripherals have been disabled long ago.

    Temperatures are good.
  3. Is it a new mobo ?
  4. its about 16 months old. I never gave it a hard time (no overclocks)
  5. Try to check your mainboard, check for any capacitor leak.
    If once, you can go into BIOS, try to check the voltage value, are they in normal range ?
  6. voltages are fine. That was the first thing on my mind. all within range.

    How do I check for leaks? what color do capacitors bleed?
  7. here some articles :

    Newly leaked capacitor has brown rusty color.

    do you have any other mainboard to test your CPU are good ?
  8. The CPU should be fine. I don't intend on testing it. It's a relatively new Core2 E6600. PLus, it doesn't look like cpu's fault so far, but the chipset's.
  9. No observed leaks anywhere on the motherboard. I double checked with a magnifying glass.
  10. 1 more thing:

    I get exactly one short beep (just like the normal "OK" beep) after posting, and before booting.
    Searched the AMI BIOS beep codes, and it says "Memory refresh timer error" - reseat the memory or replace with known good modules. I did both. The beep is still there.
  11. Your keyboard is USB or PS/2 ?
    Did you try to move the RAM stick into another slot then boot the PC ?

    After 16 months of using, how's exactly it happened when your PC crashed ? Did it just gave a BSOD then it doesn't to power up again or you turned off your PC and when you try to turn it on, the problem start ?
  12. I have had this problem when using sata on certain notebooks, and it is possible that the solution may be the same for your desktop.

    See if you can set the sata mode in the bios as IDE emulation. Usually this fixes the issue and you should be able to load windows. Otherwise, get the sata driver from the Asus website and press F6 at the start of the Windows setup.

    You need a floppy drive for this, but please note I have also had this problem caused by certain USB floppy drives being incompatible.

    Of course this may be totally of the mark, but it is worth a try.

    Good luck.
  13. When you power on, go into BIOS and observe the CPU temp under Hardware Monitor. If it keeps rising until crash, reseat your heatsink with freshthermal compound.

  14. The CPU and temps are fine, and so is the IDE/AHCI setting. has always being set to IDE.

    keyboard is USB. Did every shuffle trick possible with RAM.
    the problems started after a normal shutdown. Next time i tried to power up - that's when it all started.
  15. so far the following have been replaced trying to deal with the problem:

    1. DVD-RW drive. (pc still keeps crashing in windows setup jut before it tries to start copying files

    2. Motherboard

    3. Power supply.

    Now I'm about to stick in a different hard drive. Even though I tested the hdd used in the build in a different computer and it worked fine. Well, it didn't have to boot anything, so that's what I'll test for.

    Oh, and I'll try a different keyboard too
  16. If you had test other peripherals and they are working fine, so it's mean that your mainboard are broke. I don't know exactly how it can happen, probably an electricity spike, failed voltage regulator or can be other things.
    Anybody has any advice ???
  17. no need. it turned out that 1 stick out of 3 was defective after all, but I somehow missed it during my previous checks. This time I took the sharpie and marked them, and that's it. Now I have a working motherboard and a psu lying around.
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