About a week ago, I tried to start up my PC (home-built) and got a repeating long beep but no startup. My motherboard manual told me that this was because of a problem with RAM. I opened up the computer and dusted it out, then reconnected it and it started up and it ran normally up until yesterday. Yesterday I got a BSOD 'memory dump' screen while playing a game, so I restarted and the machine wouldn't post, just sat there. After I powered off and back on a few times, it started at the BIOS settings screen. I would save & exit, then it would post and start normally. Later it would crash again, finally to the point where it wouldn't post at all. Now when I power on, the CD and DVD drives spin up, the HD light either burns continuously or flashes, but nothing else. Sometimes I get the long beep, but more often I don't.

Thinking that bad RAM was the culprit (and unable to do any software diagnostics), I decided to start swapping out RAM sticks. I have two sets of 256mb Rambus RAM purchased separately about a year apart. Initially I pulled the newer sticks, leaving the older ones in, and the PC booted normally. However, it crashed again and would not come back, so then I swapped out the old RAM for the new sticks but still no luck. After reading some of the posts on this forum, I tried reseating the video card and CMOS battery, but still no luck. It seems that everytime I open the case and make a change, it starts up normally, but after a while (at best) it crashes again. I'm really just looking for a way to determine what component is failing (PS, CPU, RAM, motherboard) so that I can replace that component without having to replace others that are not faulty. Any suggestions are much appreciated, thank you.

Download a copy of my Diagnostic Flowcharts from here www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.

You should start on DF1, the STARTUP chart, but you will probably end up on DF4, the "NO POST" chart.

Then go here http://www.tufftest.com/free.htm
and make "TuffTest lite" "Self Booting Diagnostic Diskette".
It has its own Operating System, so any problems with your PC's own software will be by-passed and it will test your hardware directly.

Welcome to http://www.pcguide.com/ubb/pcgubb.gif

Without any specs it is hard to say, but I am guessing you may have a heat problem. When you open it up and mess with stuff, you give it time to cool down. You mentioned that it crashed during a game and that is often the case with a heat problem. You could try running a small desk fan into the open case and see if it remains stable. If it does, it is likely to be heat. I am guessing you are using a P4 and they will automatically shut down when they get too hot.

Please post details about your system if you need more help, including which OS you are using.

Well, I opened the case and verified that the CPU fan is running, tried to start it up with the cover off and a fan blowing across the interior, but it still won't work. I've also never heard any heat warning beeps coming from the motherboard, so I don't believe that it's a heat issue. I read through the flowcharts, and did end up at "no post", but I have no idea how to verify that the PSU voltages are correct. I would love to be able to run the TuffTest diskette, but if the PC won't boot to post, it won't pick up the floppy drive, especially since I have it third in the boot order, so I can't get into BIOS to change the order (and the floppy doesn't seem to be working anyway :(). Now even if I make physical changes inside the box it won't boot at all anymore, just gives me a flashing HD light and no beeps from the motherboard.

Anyway, here are the specs:
Windows XP Pro
Antec case; 330w power supply
1.8 ghz Pentium 4
Asus P4T-E motherboard
4 sticks 256mb Rambus RDRAM (two matching pairs)
40 gb HD (primary)
20 gb HD (secondary)
CD-ROM
CD-R
DVD-ROM
floppy drive
VisionTek NVidia Ti4400 video card
Creative Audigy sound card
Network card
Raid controller card (for 2nd HD)

Thank you for the replies; any other suggestions much appreciated.

Have you made any changes recently?? Especially adding any new drives? That is a lot of stuff to be running on a 330 watt power supply. Even if it is an Antec, it may not be able to keep up with the load. It might be worthwhile to try disconnecting 2 or 3 drives and see if you can get it to run that way. If that doesn't work, I would strip in back to a barebones boot and see what happens when you try to POST. That would be CPU, power, power switch, case speaker, video, one pair RAM and keyboard. If you still don't get POST, you probably have a short (if you are lucky) or a major component (video, RAM, CPU or motheroboard) is dead.

I agree that it seems like a lot of components for that wattage PSU, but I haven't made any changes in the last 2-3 months, and it has been running fine for that length of time. I'm going to go ahead and strip it down to barebones and see if I can isolate the problem. I have a feeling I'll be replacing the CPU, mobo and RAM however.:(

Oh well, thanks for the advice.

It is possible that the power supply is just wearing out from having to support all that stuff at the same time, it can overheat and gradually lose function.

The barebones will help to narrow down the problem and it may turn out to be RAM, CPU or mobo. The good thing about doing it by process of elimination is that you can avoid the expensive trial and error approach....

The TuffTest diskette would need to be made on another [working] PC.

You will see that on "DF4: NO POST" the instruction to:
"Disconnect all peripherals and system addaptor cards in base unit except keyboard and monitor" then
"Does the POST run?"
and if does
"1. Re-connect Floppy Disk Drive."
"2. Run Advanced Diagnostics."

This is where you would use the TuffTest Diskette.

If the POST does not run with a bare-bones boot then:
"System Board or something on it is faulty."
and you take it from there.

Ok, I stripped the system down to barebones and it's still not booting. At this point I'm prepared to simply replace the CPU (which I have a hunch is the problem), mobo and RAM. I'm just wondering if there's any way that I can be sure that the issue isn't with the PSU; I'd hate to order a whole new core system only to find that it was a power supply issue all along. On the other hand, I find it hard to justify spending $70 or more on a new PSU if I can be reasonably sure that that is not the problem. What do you guys think?

If you swapped the RAM around and it still didn't work, it is probably not the RAM. The only way I know to test the CPU and mobo is to swap with a compatible system and see if either works. If both work, it is back the the testing board....

You can test the power supply using a voltimeter or you can just try swapping in another one if you have one handy or can borrow one.

When you did the barebones, did you try it out of the box on a nonconductive surface??? If not, you may want to try that before spending a lot of money, it could just be a short...

I didn't take it out of the case, my experience with systems in which the motherboard is in contact with the case is that the system won't power up at all; is this not true? I am getting power, it just won't post, the motherboard won't even beep with no video card installed.

I believe shorts can be a bit more unpredictable than that, so the out of case testing is usually worthwhile. Since you are basically suggesting that you may replace the guts of this thing, it is worth it from that viewpoint in particular.

If you are getting a beep with the video card, that is POST. I am not suggesting testing without the video card however...

You are basically down to a short, the mobo, the CPU or the power supply. I would certainly want to test them all before investing in new equipment, but it is your money....:)

Does it beep with all the RAM removed?

Just a little aside here, but it may be pertinent to this discussion. I was wondering what the experience of members of the forum is in the following situation: a barebones boot that fails POST.

Assuming that the video card is okay and you are left with a choice between memory, CPU, motherboard and power supply. which is the most likely to fail and what percentage of the time.

Here's my guess:

PSU 50% - power supplies wear out, overheat, and may be damaged by shorts in other failed components. This also depends on the quality of the PSU.

Motherboard 30% - there's alot to go wrong.

CPU 15% - unless the heatsink/fan has failed, then higher.

Memory 5% - I've only seen a stick of memory fail once in 20 years and that didn't cause a failure to POST.

In this case, I would think the PSU would be highly suspect. Memory was eliminated by substitution. CPU and motherboard worked when the problem first started so they wouldn't be high on my list. Did he try to post without the video to see if it would beep?

I would first measure the voltages with a volt meter.

gwallen4,

I agree....

I just tried starting it with no RAM (and no video) installed, and received no beeps from the motherboard at all. I actually have a new core system (CPU, mobo, and RAM) on order, but maybe I'll try swapping out the PSU today just for fun. I kind of hate to buy a new PSU though since if that is not the problem I may not be able to return it and will be stuck with it. Unfortunately I have no idea how to measure the voltage of a PSU, although I do own a decent Radio Shack multimeter. How would I go about doing this?

In this thread, third post, by Yoda, is a pinout diagram of an ATX power supply.

http://www.pcguide.com/vb/showthread.php?s=&threadid=8680

That should get you going for checking the voltages.

Black = ground
Red = +5 volts
White = -5 volts
Yellow= +12 volts
Blue = -12 volts
Orange= +3.3 volts (?)
Green = power on

Turn the power on. The fans should at least come on so that you know you have power.

Turn on the voltmeter and set it to measure DC voltage. Start with an IDE power connector that is not used. Place the black lead of the voltmeter in the hole of the connector that has a black wire (ground). Connect the red lead of the voltmeter first to the yellow hole and then to the red hole. The voltmeter should read +12v and +5v respectively.

The other voltages may usually be measured at the motherboard power connector by simply sliding the red multimeter test probe down the hole where each color wire goes (with the black probe connected to any black wire as before). Really you only need to check the orange wire for 3.3 volts at this connector. If +12, +5, and +3.3 volts are all okay, then your power supply is probably fine.

Unfortunately, a low voltage measured in this way may mean a bad PSU or that some other component (motherboard, etc.) has a short and is pulling the voltage down. Therefore, the main value of measuring voltages is to eliminate the PSU as a source of the problem (if it has normal voltages).

I installed a new PSU this evening (400w) and the system is still dead. I actually don't mind having bought the new PSU since the old 330w one probably would have died at some point anyway with all of the components I have in there. I ordered a new core system and got a decent set of parts for less than I thought I would ($250), so it's not entirely bad. I'm just a little surprised because I've never had a CPU or motherboard die on me like that, but I guess I was due. ;) Thanks very much to everyone for the posts and advice, I really appreciate it.

I just quickly glanced back through, and I didn't see any mention of replacing the Motherboard battery...has that been tried??

When you get your new stuff and if it is compatible, you might want to try swapping the CPU and mobo to see if you can figure out which might have been the issue. As gwallen4 recently said, it is probably the mobo, but it is possible it is the CPU. If it is the CPU, it is probably due to a power surge or heat, so it would be good to know for future reference so you can avoid a similar problem. Also, it you find that either the CPU or mobo is ok, you could use the good part in another system or sale it on eBay....

Whyzman:

Would a bad/dead/shorted CMOS battery keep the computer from posting? I haven't seen that before but I haven't seen many batteries go bad either. I replaced one when a computer clock was losing time.

As I understand it, you just lose your bios settings, so the boot process may not proceed correctly, but you will still boot in some way, perhaps with errors, perhaps not utilizing the full resources.

I'm not exactly sure GW...

Various MBs use different ways to enable the CMOS...some apparently use capacitors to energize (as long as the PC is plugged in)...

As you mentioned, usually one would begin to see strange POST behaviors with a dying battery...

Some Macs will not post at all with a dead battery...

It's just a "cheap" shot in the dark to replace just in case it happens to be a characteristic of this particular board...

Just found this in my research:

http://www.srg.com.bs/techtalk/techtalk.asp?cmd=view&articleid=6

Note: Under the Various Symptoms...."The System will not boot."

Replaced the motherboard battery and still no luck. This system is just dead and will have to be replaced. This is the single most frustrating experience I've ever had with a computer, and that's saying a lot. :mad:

So far I haven't seen anyone recommend checking for Bad Capacitors (http://www.pcguide.com/vb/showthread.php?s=&threadid=25482). This sounds a lot like the kind of really strange, unexplainable behavior capacitors will cause. First it boots and runs for a while then quits, then partway boots...and nothing about it fits "normal" bad hardware or software behaviour.

(See, I used BOTH spellings for you picky British guys :D )

Also, since this does sound like the kind of equally strange thing power supplies will do, check the power supply for the same thing as well as for out of normal voltage range. I haven't seen any P-4 boards with bad capacitors yet, but that doesn't mean it's out of the question...but power supplies also have capacitors inside, and some are almost certainly from the same batches that are causing lots of motherboard problems, even though they are usually different voltage and uF values.

It's a shot in the dark, but worth checking.

Just curious but have you changed any jumpers on the motherboard? Are all the jumpers in the right place?