Inconsistent boot-up failure

[IMJ]

Hi,

Apologies but this is going to be a long post! I’ve got a really weird problem with my self-built computer.

In April last year I put together a PC with the following spec:

Intel Core 2 Duo E6600 (2.4GHz)
2GB Corsair XMS2-6400C4D RAM (4-4-4-12 timings)
Asus P5B Deluxe Motherboard
Asus GeForce 8800GTX Graphics Card
Antec P180b Case
Antec TruePower Trio 650W Power Supply
2 x 500GB Western Digital WD5000AAKS Hard Drives
Arctic Cooling Freezer 7 Pro CPU Fan
Creative SoundBlaster X-FI Xtreme Music Sound Card
Windows Vista Home Premium

After putting it together everything worked fine, and following the guide at the top of this forum I successfully overclocked the CPU to 3GHz, without any problems. Everything worked great for over a year until last weekend when my computer started blue-screening and restarting constantly when trying to boot Windows. I eventually tracked this down to a failed memory stick using memtest. At the same time I noticed that the two upper case fans had stopped working. I replaced both RAM modules with some newly-bought XMS2-6400C4DHX sticks, and eventually worked out that it wasn’t the fans that had failed, but using the two “Fan Only” connectors from the power supply that were causing problems. Connecting them to 2 standard connectors resulted in them working fine again.

Anyway, this is where it gets weird: I put in the new RAM/fixed the fans on Wednesday. Everything worked fine that night, and all through Thursday. However, since Friday, I am now having problems even starting my computer! I press the on button, the case and CPU fans start up as normal, but they are then followed by the graphics card fan, which never used to start up when booting. Nothing appears on the screen; in fact, my monitor actually goes into power saving mode as if there is no signal at all. Pressing restart/switching off and on does not seem to have any effect for a while, until after quite a few attempts (no consistent number), the graphics card fan DOESN’T start, and something will appear on the screen. Usually at this point it’s just a single blinking cursor and nothing else. A further restart will usually result in the system booting properly and operating as normal.

A couple of times at this stage I got an “Overclock failed! Please enter BIOS setup” message, with the options to either press F1 to enter setup and change settings manually or just press F2 to load the defaults and continue. The first time I looked manually but it had already seemed to reset it to 2.4GHz. The next time I pressed F2 and since then I’ve never seen the overclock message again even though the booting problems still occur. The CPU is definitely now running at 2.4GHz again.

Note that my case has no PC speaker so I don’t know what POST beep messages I’m getting. What’s weird is that everything seemed fine to start with, and once I do eventually boot my computer it runs perfectly fine. The connections all look fine. Has anyone got any ideas what could be the cause? The graphics card fan might point to that bit being the culprit, or is it the motherboard? I’ve also tried disconnecting the machine from the mains for a while but that had no effect. I haven’t yet tried clearing the CMOS but seeing as it can be such a pain to start my computer I wanted to get some other suggestions from you friendly people before I switched it off again!

Thanks for your help,

Iain

[peterb]

Intermittent faults are very difficult to fault find - as you are discovering! I had a similar problem recently, tracked down to an intermittent connection on an IDE cable - one of the poarallel cables was making poor contact with the pins and causing random lockups/failure to boot in hot weather.

Check all your disk drive connections - remove them and replace them. (This applies to SATA but if you have sany IDE connectors, press on the lockin g bar at the back of the connector to make sure all the pins are connecting to the pins.

Run Memtest again.

Remember that overclocking is pushing a fgiven CPU outside its guaranteed working parameters, so system instability might be expected, so it might be worth returning the bios to the default configuration - which is what would happen if you cleared the CMOS.

From the description you have given, it does sound as if the system is failing to POST - which could be the CPU failing to start, to a hardware fault. If you can connect a loudspeaker to the system, the POST beeps may give some useful information.

If you the above hasn't solved the problem, you are back to testing things individully.

Suspect areas would be PSU, or poor/displaced connections on system components. If you have a spare PSU, try substituting the one you have. Then try removing all cards and seing if the bare mobo with CPU installed will start. Then add RAM, test again, then GPU - testt again, until the system is rebuilt. You might find it easier to do this out of the case. It is a really tedious process, but in the absence of any definitive clues, it is probably the best way to solve the snag - logically and methodically.

[Will404]

This gives me the impression that your graphics card is not running correctly. Do you have access to another computer which you could test it on???

[IMJ]

Unfortunately no, I don't have access to another computer to test components with. And seeing as my motherboard has no VGA port I can't even test the computer properly with the card removed...

[Thorsson]

If you have an (very) old PCI graphics card you can use that.

You could remove the GFX card totally, but without some indicator you won't be able to tell if it's booting. Possibly you could listen to HDD activity? If it carries on for a while that means Windows is launching. That will tell you if it's the GFX card.

Now that RAM probably wants 2.1v. You can check the specs. If so did you manually set the BIOS to that figure - most usually default to 1.8v and that can cause intermittent problems.

If it's neither of these I would suspect the PSU. After all, the Fan Only headers are not working properly. I see quite a few people have had problems with this PSU: http://www.newegg.com/Product/Produc...rk=False&Page=