PC wont POST or Boot

I am increasingly frustrated. My year old homebuilt system failed to POST a few weeks ago. I performed all the tests that are required per the Sticky, on a piece of cardboard. Came down to either mobo or CPU. Got a new mobo thru Asus RMA, still didnt work. Got a replacement i7 CPU, and viola! PC working great, with core temps in the 55-60C range. For about 24hours, now its dead again. When I power up, all fans spin at max speed, the power light is on, no beeps, no signal to monitor. I have left it on for about 5 minutes with no change before I power down.

I am hoping someone can tell me what has happened and how I can fix it.
Asus P6T Deluxe
Intel i7 940 8mb cache
3x2GB Patriot RAM (6GB total)
ATI 4870x2 videocard
Samsung 1TB HD
900W PSU

Any ideas would be appreciated. Not sure how many more times I can get a CPU from Intel at no charge!
11 answers Last reply Best Answer
More about wont post boot
  1. then it's the power supply. I don't care if it's 900 watts, that makes it sound like a bad brand since it's an odd number.

    Or I suppose the RAM is also possible. But that wouldn't be able to break things by existing.
  2. my PSU is CoolerMaster UCP Series 900W. When I swapped the RAM sticks one-by-one, no beeps or POST, but when i put in a brand new CPU, everything worked, just only for a day. I am looking at replacing RAM, then maybe PSU. Any more thoughts?? Thanks
  3. PSU first. That's the only thing if it's bad that can easily break everything else. Bad RAM just makes it function incorrectly or not at all until it's replaced.
  4. Replaced PSU. Same issue. Have not swapped out RAM yet, but many people smarter than I say that is not likely the problem. Does anyone else out there have a suggestion? I am worried that if I get another CPU, im just going to burn that one again. Is it something in my build?
  5. Best answer
    If you've been testing with just the main stuff then you've tested everthing. It is possible though, if it was a bad PSU that was causing the problems, that it fried stuff. That now, the new one has nothing working to power anymore.

    That's pretty much the only thing at this point I can think of, since you've sent stuff back and had working stuff for a short time.
  6. What kind of Patriot RAM? And what's the voltage on it? Patriot DDR3 comes in anything from 1.5V to 1.9V, and if you're using anything over 1.65V you can fry an i7. If you've got a high-voltage model, I'm worried you're frying your CPU over and over.

    I would also worry about the PSU being on the fritz and frying everything beyond repair, which would make a new one not work after the initial damage was done.

    What I would start with is testing out the video card, CPU, and RAM in another machine known to be good. If one part fails, that's your problem. If none fail, it's probably the motherboard. If more than one part fails, it's probably the PSU, which has also ruined both of the other parts.
  7. I was looking at the RAM voltage. its 1.65v, and Intel specs say that a i7 940 should be 1.5 to 1.6. Howver, so many RAM specs say its "perfect" for i7, and almost all are 1.65v.

    Since I dont have another X58 mobo or i7 CPU, it looks like Im taking the whole thing in to get looked at. All of your comments have been very helpful. Thanks.
  8. There are now several cheap power supply testers on the market that are very helpful. Antec makes one that is only about $12 and readily available, will light up for each lead green or red. Simple, quick test.

    I've also seen one that actually rates the accuracy of the lines, such as an underpowered 12v that might test good but does not have enough power. I think that one was about $20, not sure who makes it - Thermaltake?

    Anyway, it's a great tool to have. I use the Antec. It eliminates a lot of guesswork to hook it up and if you find the PSU fails, you don't have to go through so much testing. I use the Antec, it's saved tons of time before.
  9. ok, so here is my plan: Just got a new mobo, CPU, and RAM. Gonna Breadboard it again, but should I place NEW items on OLD board, or OLD items on NEW board?

    Gonna do this tomorrow, I will let you know what happens. Thanks again for all the help.
  10. Best answer selected by madcircle.
  11. UPDATE: So I did a breadboard test again, this time with NEW CPU, mobo, and PSU.
    I did the entire steps, and even cross-tested old parts on new parts. What I found was that my OLD CPU and MOBO are fried. I am pointing at the OLD PSU, but havent actually had it tested, and I sure not going to connect it to the new stuff.

    RAM checked out fine, as did Video Card. So now im working on getting replacement parts RMA'd. Thanks for all your help with this!! SOLVED!
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