I had a PC system based on an ASRock Z97 chipset motherboard with a Haswell generation i7 processor and integrated graphics. Before considering the system stable, I was attempting to do a stress test using the latest version of UBCD (version V5.3.9 at the time of this writing). For these tests, I used Rufus to burn the ISO to a USB disk.
As expected, when booting from the thumbdrive, I had to select the non-UEFI version, otherwise the system would kick back to the boot menu.
Once loaded into UBCD, I found that Prime95 as well as choosing many other options under the CPU category would fail to load. Upon selecting an option, the system would immediately black screen and then automatically restart. However the Memory -> Memtest86 option worked fine and was completely stable.
I tried many things to resolve the issue such as resetting all BIOS options to default, a different thumb drive, different processor (i5, another Devil’s Canyon Haswell) and a different power supply. None of these fixed it.
As another test I booted the system into Windows 10 and it looped Prime95 without a problem, so I kept digging.
During my research, I stumbled upon a support thread on the UBCD forums, specifically this post:
https://www.ultimatebootcd.com/forums/viewtopic.php?p=11119#p11119
All of the tests that were failing were due to depending on CPUstress, which is launched by syslinux. This includes:
- CPUburn
- CPU Burn-in
- CPUinfo
- Intel Optimized LINPACK Benchmark
- Mersenne Prime Test (prime95)
- Stress
- StressCPU
- System Stability Tester
On the otherhand, the options that were functional included:
- CPUID
- x86test
- Intel Processor Frequency ID
- Intel Process Identification Utility
A workaround for the failing tests is to first select the desired test, press tab key and then change the first part of the commandt from:
/ubcd/boot/cpustress/bzImage
to:
/pmagic/bzImage
Then press enter. This managed to get the CPU test loaded (in this case Mersenne Prime test), however the USB keyboard stopped working and I couldn’t answer the prompts to begin the test. I immediately plugged in a PS/2 keyboard and was able to get it working that way.
Another workaround I discovered was installing a dedicated video card. With the GPU installed, everything worked as expected without modifying the boot loader.
However if you don’t have a discrete GPU available, the final fix I found a workaround in the BIOS.
My motherboard had an option to set the amount of memory to dedicate to the integrated graphics processor built into the CPU (Advanced -> Chipset Configuration -> Share Memory). By default this option is set to Auto. The fix is to set it to a specific value that is between 32MB and 128MB. Setting it to 256MB would fail in the same way as Auto.
Once that is set, reboot, boot up UBCD and try the CPU test again!