Why is Intel 6600T unable to boot Windows 10, but runs Windows 7 and passes Intel Processor Diagnostic Tool?

[CFinl2]

I have an Intel i5-6600T that will not boot most operating systems. I have been able to boot a recovery utility (UBCD via USB) and Windows 7 (installed via DVD to Sata SSD). In Windows 7 I can run the Intel Processor Diagnostic Utility and get a pass. It has never failed. I am unable to boot to ubuntu live USB (goes to boot menu, then black screen once I choose either install or try without install). I can not get into Windows 10 installer (USB drive, works fine in other computers), instead I get a blue screen immediately that says I have an unsupported processor. I also cant boot into another linux installer I use that works on multiple other computers I have. If I change the processor out for an i5-7600K all of the above mentioned OS or utilities are fine. I can then boot the windows 10 installer, etc. I have tried different BIOS versions (system is a Gigabyte GA-Z270X-Gaming 7). I have cleared CMOS, tried backup BIOS, loaded optimized defaults, looked through settings, but nothing seems to change. This processor runs the BIOS fine, and operates in Windows 7 fine, but can't seem to boot nearly anything else.

What suggestions can anyone make to help me figure out how to get this processor working normally? Thanks.

Further details of what I have tested:

BIOS: I have tested F6, F7, F8, and F9e. I primarily use F9e but I have observed no difference when trying other versions. I have specifically tested loading each version by loading it via Q Flash (have tested Windows based loading previously too) then loading optimized defaults. I have tried making changes to UEFI settings, but nothing has ever changed the problem. Ultimately the 6600T will only boot into Windows 7 or Ultimate Boot CD. The 7600K works with any of the versions or settings.

PSU: I have tested with two separate power supplies - an EVGA 850 W G3 (1 year old, runs my Z370 system flawlessly) and a Seasonic 500 W S12III-500 (new for working on this project). No change in behavior with either power supply.

Hard Drive: I have tested two different hard drives with this system. One is an OCZ Vertex Limited Edition 120 GB SATA II drive, the other is an Adata SX8200PNP 512 GB M.2 NVME drive. Each drive seems to work fine. I have run multiple operating systems from the NVME drive. The Vertex currently has Windows 7 and runs fine with either processor. I have tried booting into installers or live Linux distress with no hard drive. There seems to be no correlation between hard drive and processor failure.

Boot Devices: Windows 7 was installed via DVD from a SATA Blu Ray drive. I have tried Windows 10 from a USB drive, Ubuntu from a USB drive, ipFire from USB, and Ultimate Boot CD from USB. I have tried multiple USB ports on the back panel and ports connected to the internal USB 2.0 header. All of the boot devices function 100% as expected with the 7600K. Only the Windows 7 from DVD and Ultimate Boot CD work via USB from the 6600T. I have also tested several of the USB installers on my Z370 system and they have worked fine.

Operating Systems: The 6600T is able to run Windows 7. I have switched the 7600K into the Windows 7 install and the system functions. I tried installing Windows 10 with the 7600K and then booting with the 6600T, but I once again get the unsupported processor error screen. I can not boot from my ubuntu drive. The boot menu starts and with any selection I get a blank black screen. Windows gives me an immediate blue screen with an error message that I am using an unsupported processor. ipFire gives me results similar to Ubuntu. The 7600K works fine with everything.

RAM: I am primarily using G Skill Ripjaws V (F4-3000C15D-16GVKB), which is on the QVL list. This RAM was used for about 1 year in my Z370 system with no problems. I have run MemTest for a bit with the 6600T and found no errors. I have tried one stick and both, in all combinations of slots. No difference with any changes. I also tried G Skill Sniper X (F4-3200C16D-32GSXKB). No different. I have tried default settings and XMP profile. No change.

GPU: I have tested with integrated graphics, an EAH4350, and a GTX 460. There is no difference between integrated graphics and discrete GPU. I mainly use integrated graphics to limit variables.

Case and Cooling: I am running open air with the motherboard sitting on an anti-static bag on top of the box. The CPU is being cooled with a Corsair AIO. Typical CPU temps are in the low 20 C range.

Motherboard: I have also tested most of these components in a Gigabyte GA-Z170X-UD5. I have tried BIOS F2, F5, F20, F23a. I previously had the 6600T unable to POST, but with my most recent round of testing gave results identical to the Z270 board.

[Leonardo_C_Intel]

Hello CFinl2

Thank you for posting in the Intel Community.

Can you try installing Windows® 10 using a different a hard drive on the system? If it is possible using an HDD.

Make sure you are using the latest BIOS for the motherboard (https://www.gigabyte.com/Motherboard/GA-Z270X-Gaming-7-rev-10/support#support-dl-bios)

Regards,

Leonardo C.                        

Intel Customer Support Technician

Under Contract to Intel Corporation

[CFinl2]

Hi Leo C,

I have used two different drives so far - one is an older SATA II SSD, the other a NVME drive. Both drives have functioned flawlessly in other systems or as soon as I switch the processor out in this system. I have also tried booting with only a bootable USB drive and this system still won't boot. I currently have the Windows 7 install running from the SATA ssd. I don't have any other drives available to try in this system currently.

The motherboard is running BIOS F9e now. I have tried F6 as well. I usually flash from the BIOS tool, but have tried from Gigabyte's Windows based tool. I also flashed the BIOS with the 7600K incase there was a fault with the 6600T. I forced the system to try the backup BIOS, no difference.

Thanks for the input - anything else I can try?

[n_scott_pearson]

My initial reaction to every one of the symptoms you have provided is that there is a problem with your board's BIOS. Are you running the latest available BIOS? This feels like the BIOS does not recognize, support or have microcode updates for this processor. Is it specifically included on the list of supported processors for this motherboard?

...S

[CFinl2]

Thanks for the reply n.scott.pearson,

The processor is specifically listed by Gigabyte as supported starting at BIOS F3. F9e (currently running) is the newest available. I really cant make heads or tails of it either. I have a Z170 board as well, and on that board the 6600T won't boot, but the 7600K will. Thanks again.

[Leonardo_C_Intel]

Hello CFinl2

Thank for completing the testing given the test and the outcome I would recommend contacting Intel® Customer Support (https://www.intel.com/content/www/us/en/support/contact-support.html) for warranty options.

Keep in mind that this is not a common failure of a CPU so if the replacement that is brand new unit has the same issue we would recommend you might have to go with the motherboard manufacturer and even Microsoft

Regards,

Leonardo C.

Intel Customer Support Technician

A Contingent Worker at Intel

[CFinl2]

Hi Leo C,

Unfortunately this processor is not covered by warranty (I purchased it used and the partial serial indicates it was a tray CPU). I do appreciate you taking the time to help. I have also reached out to Gigabyte incase they have any input.