Can a CPU fail but still run?

This is one of the most bizarre problems I've ever run into. A few months ago, my desktop PC running Windows 7 Pro 64 SP1 started having issues with Windows Updates failing. Figuring it was a software issue, I tried Microsoft Fix-It with no luck.

I finally broke down, reformatted the HDD and reinstalled Windows. It installed about the first 10 updates but the problem reoccurred. I tried a second HDD; same problem. Ran Advanced System Care, still no luck. Based on this, I'm pretty much ruling out a software or malware issue.

Ran Memtest for about 40 minutes - no memory issues noted.

The PC will run for a few days nonstop (sleep and turn off HDD disabled) without shutting down or going to a BSOD; however both IE11 and Firefox are unstable and will stop/restart without warning.

Here are the two smoking guns left:

* About 10% of the time, the PC will not start/restart properly. The light and fans come on, shut off, turn on again and repeat. Turning off the power supply will fix the problem for several more startups. Once back on, it will run for days.

* The CPU is an Intel E8400 - yet, an Everest report lists it as an Intel Xeon III. rolleyes In the BIOS, it shows correctly as an E8400. It is a Gigabyte EP43-UDM board with the latest BIOS.

I'm thinking either the CPU or motherboard are unstable to the point of causing multiple and severe errors.

Has anyone else had an experience like this - and, if so, any ideas on what to try next? Thanks in advance for your help.

 

I would suspect the PSU if it's old then check the motherboard for signs of failure like bulging capacitors.

 

+1 to power supply. Not guaranteed to be your problem but a good starting point if you have a spare on hand that you can swap
I had an overclocked i7 desktop intermittently BSOD and also sometimes it would spuriously reboot. I thought there was a possible memory bus timing error but it kept passing memtest and all CPU and system diagnosticss so in frustration I left it running Prime95 on maximum stress test with my recording voltmeter monitoring the 12V and 5V rails. After 2½ days running @ 60°C the BSOD finally occurred and it was at the exact same time as the 12V rail dipped to 8.6V and the 5V rail dropped to 4.1V :confused

Long story short after lots of checking if anything had dragged the rails down and with nothing found, I decided to replace the 750W Corsair power supply and it has been running flawlessly ever since rolleyes which is now about 6 months :cool
When I tested the old power supply separately with my digital power supply tester it checked out perfectly even on long term tests but if I put it back in even a low spec i5 pc it still randomly BSODs so I got it exchanged under warranty and all is good

The motherboard you quote is one of the Ultra Durable Gigabyte range and has solid caps fitted as well as beefed up onboard power regulation so is less likely to be caps or onboard power problems.
Just a thought but have you tried reseating the CPU in its socket as sometimes one of the BGA (ball grid array) pin connections can go intermittently high resistance and fan vibration can exacerbate the problem. I have many of this series mobo in service and so far (touches wood) have had zero problems. When released they were a low priced board with solid mid range performance

 

If the CPU fails, the computer will either boot up and then shut itself down. Or when you power on, it will immediately power itself back off.

As for being ID'd as a Xenon III CPU, that is correct. The Intel E8400 is also the same as a E3110. If the CPU does not meet Intel's criteria, it is downgraded. Both CPU manufacturers have been doing that for years with their CPU's. If they still meet certain criteria, but not all. They will downgrade to a certain type.

"The Xeon Processor E3110 and the Core 2 Duo both have 2 cores, and so are quite likely to struggle with the latest games, or at least bottleneck high-end graphics cards when running them. With a decent accompanying GPU, the Xeon Processor E3110 and the Core 2 Duo may still be able to run slightly older games fairly effectively.

More important for gaming than the number of cores and threads is the clock rate. Problematically, unless the two CPUs are from the same family, this can only serve as a general guide and nothing like an exact comparison, because the clock cycles per instruction (CPI) will vary so much.

The Xeon Processor E3110 and the Core 2 Duo are from the same family of CPUs, and thus their clock speeds are directly comparable. That isn't particularly helpful, however, as the Xeon Processor E3110 and the Core 2 Duo provide identical clock rates and thus extremely similar performance."
http://www.game-debate.com/cpu/inde...on-processor-e3110-vs-core-2-duo-e8400-3-0ghz