Slots 3+4 don't work and the 24 pin motherboard connector won't boot

I just bought 2 more sticks of GSkill 2x1GB DDR2 240-Pin RAM. I already have a set of these in my computer(Slots 1 + 2). I installed the 2 sticks of RAM, no POST. Computer boots but no POST, just a black screen.

Went back, took them out. I moved my existing RAM to slots 2 + 4, no POST. Slots 1 +2, no POST. Slots 2 + 4, no POST. I messed around with ECC settings and voltage, no POST.

I'm thinking maybe the slots of RAM are bad? My processor is an AMD Phenom II X4 9950 BE @ 2.6 GHz stock and my motherboard is an ASUS M3A79-T Deluxe. Also, in CPU-Z I'm having some funky things show up. For example...

The two RAMs dont add up. It seems to me, the second bank (slots 2 + 4) are bad?

Also, the motherboard has a 20+4 pin connector. Right now, I can only boot using the 20 pin. If I put in the 4 pin from my power supply, the fans turn on for a fraction of a second and everything turns off. The motherboard power light still stays on though, showing I have power. The only way to turn my machine back on is to unplug the +4 pin, unplug my power cable for 10 seconds, and replug and start the computer.

Any help guys? Are these two issues related?
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  1. Bump................
  2. Hey Diamons,
    I'm no expert, but I think we have a similar problem. I'm also upgrading and I tried to use a 20 pin power supply on a new mobo which requires a 24 pin ps. I don't think your problems are related.
    If I'm correct you'll need a 24 pin power supply and if your trying to use DDR2's on a DDR'3 board though they are supposed to be okay my experience was that the pins on the sticks were configured at least on the ASUS M4A78E-T , so they do not accept DDR2's.
    The good news for you is if I'm right you'll only need to change your power supply.
  3. Hmm I'm running on a DDR2 motherboard, thanks though.
  4. Not being able to use th +4 pins of a 24 pin main power plug is a problem, but not real serious.Most modern computers really do not need the extra pins.

    History lesson:
    Long ago, they had 20 pin PSU connectors and everything was powered from the motherboard. Components became more power hungry.

    PSU connectors went to 24 pins. The four extra pins were one each 3.3, 5, and 12 volts and a ground. CPU's got their own 12 volt connector and power through the main power plug dropped.

    Video cards got bigger and got their own 12 volt power connectors and 5 volt power through the main power plug dropped.

    RAM went from SDRAM (3.3 volts) to DDR2 and DDR3 (1.65 - 2.2 volts) and 3.3 volt power through the main power plug dropped.

    12 volt power through external (to the main power connector) connectors is doing all the heavy lifting.

    THe memory problem is more serious.
  5. Alright thanks for that bit of information :) Is there a specific reason as to why it won't boot with the +4? In speedfan, I see for my

    -12V: -5.94V
    -5V: -2.09V
    +12V: 10.18V

    I'm assuming my PSU is dying because the bottom fan on my PSU is not working. I still have warranty on this and plan on returning it in a few months.
  6. Speedfan frequently gets the voltages wrong. What does the BIOs tell you. It should be in something called "PC Health".

    If your 12 volt output were that low, your system would not boot. Modern PSU's no longer have a -5 volt output, so that reading is bogus. The -12 volt output is usually generated by a three terminal regulator chip. They either work or do not. there's very little to go wrong with them.

    Check your motherboard manual for directions on where 2 sticks of RAM should go. Work with the two sticks until you get your problems sorted out.

    Back to the PSU ...
    It sounds like you have a bad PSU. I said you do not need the +4 plug, but it should not shut your computer down. Don't wait. Return it now.

    Then when you get the new PSU (get a good brand), if your system still does not boot:
    Work systematically through our standard checklist and troubleshooting thread:
    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.

    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: 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.
  7. Thank you so much for all your help. I'm going to RMA the PSU and the motherboard in a week or so.

    I think the motherboard is defective because the CPU_FAN pin doesn't work but FAN_1 and FAN_2 work, so the computer always boots with an error message.
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