Intel Processor Diagnostic: Screen goes black, but recovers. Test passes. (i5 6600k at Stock FREQ- BIOS Controlled VCORE)

[JPlou]

Been having some PC trouble and just going through the motions, documenting any suspicious behavior. I want to know if this is typical and/or a non issue? I've ran the CPU Diagnostic tool looping for hours upon hours lately, and occasionally the screen will blink out (I'm not running IGFX, but off a GTX970) go black with mouse cursor visible and responsive, then everything will come back. This is during the CPU Load test. PC function appears uncompromised following this issue.

The 6600k Passes the test, and in the cumulative 20+ Hours I've looped the test, it has not failed in any documented fashion save this one, perhaps benign anomaly. My current suspicion is a RAM problem, but I don't know if RAM would induce this kind of effect, or if this is just a quirk of the test, or maybe some latent issue I don't know about.

I have overclocked the processor in the past via unlocked multiplier and uncore. 44 Core Mult with 42 Uncore it ran with perfect stability at a peak of 1.224V with temperatures well below anything that could even be considered dangerous, even in the scorching California summer. I returned everything to stock via CMOS reset as part of ongoing diagnostic process. No change in presenting symptoms.

Tangentially related, only included If it would help at all: my issue that has prompted my diagnostic steps is an intermittent stuttering-freezing effect on my PC. Similar to what one might expect if they had a hardware bottleneck and were waiting for a resolution of something like a pagefault. The system doesn't crash (Though it has frozen and crashed in the past, it is not a common occurrence) and operates at a tolerable level for basic function, but an intolerable level for things like gaming. This problem doesn't happen super often. Maybe for a couple hours per day, usually after the PC has been on for 1+ Hour, and it sometimes, perhaps most of the time, resolves itself in an hour or two. Yes, my initial suspect was a driver, or some software issue, but programs like LatencyMon, as well as a reformat and driver update has never addressed the issue. This problem started happening early march, shortly after a RAM upgrade (the suspect RAM has been removed, stability did improve, but the issue still creeps up occasionally) If I had to guess, I was shipped the wrong RAM kit, and I loaded the XMP profile for 2400mhz for a 2133mhz and after a few weeks of running, suffered RAM damage or motherboard damage, but we all know the only way to be sure is trial-and-error. ( have a brand-new kit otw) The 6600k's IMC passes testing, as my biggest worry was a poor voltage setting could have cooked it.

Additionally, I am curious if there's any kind of CPU Failures the Intel Processor Diagnostic WOULD NOT find, or if my CPU passes the Diagnostic, I can rest easy knowing it's at least not the processor. (Which I voided the warranty on by overclocking lol)

I ask because I know Memtest and Window's Memory Test are highly imperfect diagnostic tools. If they catch something, you can be sure you have a problem, but if they pass, you can't rule out a memory problem. I hope Intel's CPU diagnostic doesn't share this exception.

[idata]

Hello Hobo_Misanthropus,

Thank you for contacting Intel Communities.Thank you for bringing this to my attention. In this case, I would recommend uninstalling the graphics card and run the Intel® Processor Diagnostic Tool again to see if you keep on having the same issues, to do this you may install the https://downloadcenter.intel.com/download/26836/Intel-Graphics-Driver-for-Windows-15-45-?product=88345 latest Intel® HD Graphics 530 driver (after uninstalling the graphics card) in case you don't have the driver installed.Bear in mind that altering clock frequency or voltage may damage or reduce the useful life of the processor and other system components, and may reduce system stability and performance. Product warranties may not apply if the processor is operated beyond its specifications.I hope this helps.Best Regards,Juan V.

[JPlou]

I've actually tried to run with just the IGFX before, and the screen completely blacked out after a few minutes of Idle time, including on a restart (NO BIOS, but the System did appear to continue to POST and boot). Mind you, I was able to initially boot the system with IGFX just fine, but when the screen blacked out in that case, I had no signal at all until I reverted back to the Graphics card.

That was the first time I had ever used the integrated graphics on the chip. But if my suspicion is correct and I'm encountering some kind of memory error (DDR4 not IMC), I don't anticipate the IGFX on the CPU to function normally, as it's using the system memory as its VRAM. So a failure wasn't entirely unexpected.

I do not encounter this temporary black-screen issue if I bump the voltage up on my PC manually. I know you say (And have to say) that adjusting voltages is dangerous, but my auto voltage control seems to suffer from considerable VDROP (around 0.2V) with 1.120V Being about the peak VCORE while VID may request as high as 1.148V.

When I first built this PC, the BIOS set the Voltage to 1.175 So I am suspecting age-related VDROP might be the cause here. I am very conservative with VCORE voltages, the highest run through this 6600k is 1.25V (1.236 actually because of VDROP). These voltages don't even alter the temperatures, and an absolute peak-burn-in temperature is, on the hottest core, still sub 60C.

Manually setting the Voltage to the upper limit of what the VID seems to be requesting stops the blink-out while running on the GTX970. But the full-blown blackscreen will happen anyway if running off the IGFX even with higher (went as high as 1.25V). Again, probably because I have a memory issue or perhaps even because my drivers are out of date. (Never used IGFX until a few days ago, and the CPU is about a year old)

[idata]

Hi Hobo_Misanthropus,

Thank you for the information.Does this issue happen (black screen) while playing games or running another program?Regards,Juan V.

[JPlou]

Not in any games that I have observed. Most games don't top out the CPU though, even without an Overclock.

It may (Running off imperfect memory here) have happened once while doing a burn-in on Prime 95. But I can't for the life of me remember with certainty. Again, it doesn't seem to happen now that I've put my voltage up a bit more. My motherboard (Gigabyte GA-Z170X-UD5) has notes in the BIOS updates (F22) about VCORE adjustments, so perhaps the automatic voltages are to blame here. I'm currently on F4 BIOS, so quite a few behind.

I don't intend to flash the BIOS unless I continually have problems, I don't have an uninterruptible power supply available, and I have terrible luck with brown-out/black out timing.

[idata]

Hi Hobo_Misanthropus,

Thank you for the information.Then, to be sure, the issue went away by changing the voltage?Regards,Juan V.

[JPlou]

Yes, so far I haven't had a recurrence with more aggressive voltages. I'm on a GA-Z170X UD5 REV1.0 Motherboard from gigabyte on Bios F4. And I've been having some BIOS troubles causing me to have to manually adjust a lot. So if it helps anyone else, playing (Very carefully!!!!) with Voltages might help. These BIOS problems might be caused by bad memory, settings may be getting corrupted in the UEFI and not saving to the BIOS chip properly, but this is pure speculation on my end. For my 6600k, my stable voltages appear to be a manual target of 1.18 (Without Vdrop) or 1.2 with Vdrop. However, this probably varies slightly for each piece of silicon. (This is with no Overclock aside from Turbo Boost)

My Intel Turbo Boost wasn't working for a while either, but after clearing CMOS (Through the remove-battery method, not button/jumper) and then re-loading optimized defaults, I have also restored intel Turbo Boost to normal function. So it does seem BIOS is the source of most of my trouble.

My CPU cores slip to 800MHZ despite being set in Windows 10 to always operate at max frequency all the time through power management adjustments (So with Turbo, 3.6-3.9) however, this is another type of behavior that is voltage sensitive. I'm operating on a more dynamic voltage currently, instead of forcing base voltage to like 1.175, and the voltage is stable when the system is under load, so I'm not worried about the 800mhz slips. With voltage fluctuating as low as 0.132(idle) and peaking at 1.2(Load) it's not surprising that this is happening.

Right now I'm waiting on an RMA memory kit to see if some of these issues go away once I swap memory in. I still haven't got the IGFX to work since first attempt caused the screen to crash. Memtest86 showed no memory errors in 12hours, but I suspect it's an early address error, so Memtest wouldn't catch that.

[idata]

Hi Hobo_Misanthropus,

Thank you for the information. Please be aware that if you keep on having issues after replacing the RAM, the processor could be damaged by now because OC.Please let me know if you need further assistance.Best Regards,Juan V.