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What is the problem?? Mobo, Memory, PSU, or CPU?

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July 8, 2009 8:48:06 PM

I need some help. I'm trying to determine which component is the problem and would like some expert opinion...

I'm working on a new system build. It's been a few years since I've needed an upgrade. Here are the components:
Mobo-- MB ASUS M4A78T-E AM3 790GX/SB750 RT
CPU -- AMD|PH II X3 720 BK AM3 2.8G RT
Memory -- MEM 2Gx3|OCZ OCZ3G1600LV6GK R
PSU -- CORSAIR|CMPSU-450VX 450W

I'm just trying to get the computer to boot at this point. Will worry about the rest of the system once that's sorted.

I'm using integrated video, so no additional components are inserted into Mobo.

When I power on the machine, the fans spin but nothing displays on the screen. I've tried clearing the CMOS, moving the RAM, powering with just 1 stick, re-seating the CPU, etc. But nothing works. Ive also checked that the mobo is on the copper screws on the case. Everything looks good, as far as I can tell.

Next, I tried a different outlet, thinking maybe it was a power/outlet problem. On one outlet in the house, the Power Supply wouldn't supply any power to the Mobo. Maybe it was a grounding issue, but adding this detail in case it provides any clues.

Any suggestions on what to try next? What's the best way to determine the source of the problem? I can't imagine that more than 1 component is bad. I'm leaning toward the PSU, but maybe it's a CPU + Memory combo with that motherboard? Or, motherboard BIOS needs update?

Would be grateful for any advice. Thanks in advance.
July 8, 2009 9:16:14 PM

You need some kind of instruments. there are some PSU testers out there and you could get something like the Kill A Watt from Newegg. I'm not sure how much your set up should be drawing from the wall, but if your system is drawing 50 Watts or less, then your processor probably isn't drawing any juice.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

If you have a video card, you could try that in case the onboard video chip is bad.
July 8, 2009 9:37:53 PM

Stock DDR3 voltage is 1.5V and your memory requires 1.65V to operate..... you need to boot it with a stick of DDR3 that only needs 1.5V to operate to make the necessary changes in the bios to be able to use your "killer" memory......
July 9, 2009 3:55:23 AM

shabaa said:
Stock DDR3 voltage is 1.5V and your memory requires 1.65V to operate..... you need to boot it with a stick of DDR3 that only needs 1.5V to operate to make the necessary changes in the bios to be able to use your "killer" memory......



This sounds reasonable. Ive tried everything else. When I remove all memory sticks from the motherboard, I get 3 beeps. With any memory inserted, I get nothing. Leads me to believe that it's a problem with the memory configuration.

So, if I get DDR3 that operates at 1.5V, I should be able to boot the system and change the BIOS to allow the mobo to use 1.65V memory.

Would I be better off RMA'ing the 1.65V memory and getting something more compatible with the AMD AM3 motherboard? Thoughts?

Thanks!
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