Sep 27, 2011
I have recently purchased all new components for an AMD ATX build.

Installed all components, connected power lines, & plugged in, switched PSU on.... nothing, no LED lights on motherboard, nothing whatsoever....

-Antec P183 (case)
-Asus Sabertooth 990FX (Motherboard)
-Fatality 550W OCz (PSU)
-Phenom II (Deneb black edition) 3.2
-Radeon Sapphire HD 6870
-8G GSkill RipJaw DDR3 149000
-1 Cavalier 500G HD
-1 Seagate 500G HD
-Samsung Blue Ray ROM DVD RW drive
-USB Card Reader (internal)
-Rosewill 1T2R PCI Adapter (Wireless) -not yet installed-

This is my first computer build; but I have studied A+ CompTIA & am familiar with all procedures involved.
I put all of the pieces in place (minus the wireless PCI card) and connected all power cables. I had forgotten to snap in the rear panel for motherboard connections (and did a little rough maneuvering, as all pieces were in place), I don't think this damaged the mother board, (and if it did, still would imagine LED lights would come on to an extent).

Any suggestions, tips at what I might need to check, ways to decide if this is a PSU, Motherboard problem??



Hard to troubleshoot from here, but one thing strikes me. If you forgot to put the I/O shield in place before installing the motherboard, how did you get it in without removing the board? Push it in from the outside? It must be installed from the inside for proper shielding. But I presume you know that.
The reason I ask is because those little fingers that are suppose to ground the I/O ports' enclosures are designed to lay on against the tiny I/O housings. I had a board once that I installed and had gotten one on the fingers inadvertently inside one of the ports. That grounded one of the circuits and the board wouldn't come on. You might check that.
Another common problem is putting in more motherboard standoffs than you needed and inadvertently having the unused one ground the back of the board.
When I put together a new build, I like to first set the board on the insulated packing material and plug in the board's PSU cables (don't forget the CPU power cable), and attach the video output to the monitor. Then either use the on-board pwr button or short the 2 power switch pins to start the board and check for video, BIOS, etc. If the board doesn't come on in that basic configuration, it's a good bet the board is defective.


your 550w PSU is going to struggle to power all that.

see if you can get the machine to post beep with ONLY mobo, psu, CPU & Heatsinc connected.

NO Video Card, Hard Drives, ROM drives or RAM.

it should give you post beeps. (if system speaker is connected)


The no boot new PC build tutorial at the link below should help. The PSU/Vid card info. will help you accurately determine what PSU power you need including 12v rail amps. and what PSUs are a quality unit.


As far as PSUs are concerned, be informed. Before you buy any PSU read accurate, objective PSU reviews at reputable sites such as www.jonnyguru.com or www.hardwaresecrets.com on the EXACT model PSU that you are interested in as some brands have good and poor quality PSUs.

You can also get an accurate rating of how much PSU power is required for your current or future system at the PSU calculator link below. Once you know the total PSU watts required then you need to confirm that the 12v rail has enough amps. to support your Vid card(s) and the rest of the PC system.

There are several websites that show the Vid card power consumption in watts. Divide the watts by 12 to determine the amps. required on the 12v rail(s). Add 15 amps for the rest of the PC on the 12v rail and you now know the Minimum total 12v rail amps required under full load. It's best to have at least 5-10 amps. reserve on the 12v rail available under full load so the PSU is not loaded to 100%.

It's also worth noting that people often misunderstand the 80% power rating. This is a rating of the PSU's energy efficiency not it's output. 80% plus PSUs use less grid power to produce the same PC power. If it's 80% Bronze, Silver or Gold the cost savings on electricity is pretty small between Bronze, Silver and Gold unless you are paying very high rates for electricity so any 80% rated quality PSU is fine even if not Gold. For those who leave their PC on 24/7 a quality 80% PSU is a good investment.





No. One of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 - a card with similar power requirements to the 6870, a Gigabyte EP45-UD3P motherboard, 3 hard drives and an optical, and a Soundblaster card all powered by a Corsair 750TX.

Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% PSU efficiency, the system pulls 300 watts from the PSU.

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


If no luck, continue.

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. The green wire should also have 5 volts on it. It should go to 0 volts when you press the case power button, then back to 5 volts when you release the case power switch. 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.


Sep 27, 2011
Gentlemen, many thanks for all of the excellent feedback. I regret to inform you that the culprit here was far less advanced than most of the great advice given....

[drum roll...]

I had managed to plug in the main power cord upside down; In light of this, I believe I'm relatively lucky that I did not fry the board when I attempted to power up. I unplugged all components to evaluate where the problem could lie, and amidst all the complexities... I noticed the error being the simplest of all. Anyways, glad to be a part of the community (I've read these forums for a long time prior to joining); I'm sure we will cross paths with speculation, evaluations, and troubleshooting down the line (I will do my best not to cry wolf about mis-plugged power cables again!

Again, thank you for the feedback; See you in the forums!