Computer will not turn on!

[jnelsoninjax]

Just had this PC dropped on me from a friend, who indicated that last night everything was working fine, left the room and when he came back the system was off, and would not turn back on. The power supply is a 550 Watt Ultra and the MB is an Asus with 2 2 GB corsair RAM sticks and an XFX Geforce 8600 video card, I have tried re-seating everything, and I changed out the power supply. On the new power supply which is only a 400 watt, the computer turned on, but since I had nothing but the ATX power plugged in, I do not know if it would have worked, now that I have everything plugged in (HDD,DVD, Video card) nothing will turn on at all. The testing power supply is a modular one, so I removed everything except the ATX power and nothing happened, no power, no CPU fan running, not even the power supply fan is running. I pulled the DIMM's from the system that will not power on, and placed them into a working system, and everything powers on no problems. I also re did the front panel block on the board just to rule that out. I have checked all the other hardware (HDD, video, DVD) in a working system, everything powers on, the only thing that I have not yet attempted is the CPU, which I'm begging to suspect, due to, when I pulled it the first time after receiving it, there appeared to no thermal compound on it, and the way the symptoms were: Normal browsing online, let to use the bathroom, cam back ~5 mins latter, system was off, would not turn back on, also inquired about any power issues (brown-outs, etc) and was told that all the other equipment was still on. Can someone come up with an other idea? I am at a total loss here! Thanks!!

[brayden]

So did the graphics card work fine? recently i had a graphics card burn out and stuff my whole motherboard up

[findingmyzen]

I had the same problem with my old computer, the motherboards small pillar like cylinders all opened up and rusted, but I did not know it till after it was checked out. We first changed out power supply, still didn't work, then changed graphics card, still didn't work and then finally looked at motherboard and realized it was the culprit. Amazingly though, the CPU was fine.....but mine did the same thing, turn on but not actually work, the fans in the power supply worked, graphics card fan worked but computer wouldn't boot.

Doesn't the cpu need the thermal compound?

[Rush]

Yeah, it does need need the paste. A lot of times, though, on the big names like HP, Dell, etc.. they aren't exactly generous with it and after a couple years it looks more like a stain than anything else. Especially if the heatsink is all dusted up.
If the cpu isn't properly seated, it will heat up and cause the system to crash. Usually the computer is designed to do that. Most of the time (but not all), it will boot back up and crash again and again. Your buddy be pretty unlucky to kill it in one shot out of the blue.
It sounds like it's on the motherboard. The MB should still carry power even if the cpu is fried. If I understand you correctly:
1. You have tested each of the original components effectively on an alternate system except the PSU.
2. You ran put the test PSU in, connected only the 20/24 pin to the board and nothing else and the board took juice.
3. You reconnected all the original components, connected them to the test PSU, fired it up and got absolutely nothing, nada, zip, zero, ziltch. No pop, no click, no cpu fan spinning or even twitching. Silence.
4. You disconnected everything and re-ran the exact same configuration as you did in #2, with the exact same result as in #3.

(IF's)
If that's true it's most likely a problem on the board at one of the component interfaces (SATA, IDE, PCI...) and it might have blown up your test PSU. (It's also probably a Dell Dimension)
If each of the components achieved stability in a different system then the component side of the interfaces are good.
If config #2 took juice and #3 didn't, then something is going wrong as the power hits the component interfaces.
If after trying #3 you can no longer get #2 to take power, something changed after power hit that interfaces. On either the PSU or the Mobo
If it worked the first time with the test PSU, then the initial time that the problem occurred, at your buddies house, it did not cause a permanent change to the motherboard.

First, put your test psu in another system and see if its blown. Also, test the old one if you haven't already. If the test PSU is blown then the motherboard is trashed, and he'll need a new one.
If it's not blown or you have another, put it back. Disconnect everything. Put the thermal grease on and re-run configuration #2, (PSU --to--> 20/24, cpu fan, front panel power I/O only--- no ac97, HDaudio, no USB) with the A/C power cable disconnected from the PSU, but still plugged in to the wall. Get it as quiet as you can and get comfortable, you will have to do this several times.
Put the power cable to the PSU and see if you can hear the power hit it. Power the system and see if it does anything. If it doesn't pull the power from the PSU and see if you can hear the power leaving the PSU. Pop the MB battery, clean all the interface terminals, put the battery back and try again.
If it does power up, power it down and get an alternate set of SATA/ IDE cables. Power it up over again component by component until it doesn't.
Start with basic I/O. AC97, usb, fans, then DIMM's (one at a time), PCI. If you get that far, break out new cables and go: floppy, optical drives and HDDs.

[ > = before ] (new cables>old cables slaves>primary power>data

If at any point you hit a point where it will power with the new wire first but will not with the old one, he owes you at least a twelve- pack. A $15 problem.
If you hit a point where it wont work with the new cable, the problem is at that interface on the board.
Try skipping that interface and continuing. Unless it's something like the primary IDE channel or entire southbridge, you may very well be able to skip the interface and still be ok. Then he only owes you a six pack, but he should let you keep the drive. (If he brought you his computer the morning after it croaked, you are obviously "the computer guy" and it will wind up in someone system sooner or later. Probably his.)
If you cant skip it and trying it again with a brand new wire wont work, the board is toast and will need a new one. Then he's screwed. Depending on how old it is getting a replacement for the original will expensive and a newer or alternative model will most likely include new RAM also. That's closer to a $300 problem at least. If it's more than 7 or so years old your best bet might be to try to find an old one on e-bay with like no hdd or ram and pulling the mb out of that.

[jnelsoninjax]

OK, so here is the really odd thing, this morning I pulled the CPU from the DOA system and placed it into a working one, and took the working ones CPU and placed it into the DOA system, poof! They booth magically started up and running, at least power wise (CPU fan and PSU fan), I do not know what caused them to start working suddenly but they are! Also BTW the system is a bare bone kit build by my roommate, so @Rush, your theory is a valid based on the little info I provided, I never seem to remember to mention that the system is a custom build!
Edit: Now I changed the SATA cables out, and swapped video cards, the system boots to windows, but either freezes at the loading screen or BSOD's with a Memory Management error! I'm leaning toward the PSU being the culprit, because when I tried to make changes in the BIOS, after about 1-1 1/2 mins it freezes. Anybody have any additional theories?

[Rush]

Try changing the RAM. See if good RAM will work in the DOA.

[Raymond]

Have you ever thought that it might be the motherboard itself?

I always narrow down the problem by only connecting the necessary hardware to get it started.
CPU, Mainboard, 1 piece of working RAM and display card (if there is a built-in display, use the built-in one and don't install the external graphics card)

If the BIOS can hang after a minute with minimal hardware, it shouldn't be power supply. It's either CPU, RAM or mainboard. You can test the ram by running memtest http://www.memtest.org/ on a working computer.

If there's no problem, now u know it's either CPU or mainboard. When it comes to either one, 70% of the time is the mainboard's fault.

[jnelsoninjax]

I have discovered the problem is the CPU and PSU, the RAM is from a working mainboard, the video card is also, the symptoms are: Upon booting to Vista DVD it freezes and then BSOD's with generic error (no message, just memory location info), and according to another tech friend on mine, that is indicative of CPU failure, I advised my friend to purchase a new PSU and a new CPU, and I will RMA the old PSU and CPU to the respective companies.