This article is probably not very relevant anymore, considering the age of the platform and rarity of the CPU, but nevertheless, it can be useful for historical purposes or if someone happens to have the CPU mentioned below. Back in 2012 I bought X79-based Sandy Bridge-EP platform (based on ASRock X79 Extreme4-M motherboard) together with the engineering sample CPU having a QAFF S-Spec (supposedly 4-way Xeon E5 which doesn't have corresponding production item). Though the CPU was recognized by the motherboard and system initialized successfully, over time however, it proved to be quite unstable and stressful to use. Two main issues were:
The second problem was easier to identify since the problems started soon after I replaced older Radeon 2400PRO based graphics card with more modern Radeon RX460 one. Windows boot process locked out immediately on first reboot after AMD drivers were installed. Linux boot process froze as well on loading display server (X.Org). In both cases, the only way to continue was to reset the system. By default, BIOS was selecting PCI-E v2 for the graphics card. Reducing PCI-E to version 1 helped to load the desktop environment in Linux but system performance was unstable up to complete system lock out. Windows was still crashing regardless of the PCI-E mode set in BIOS. Explicitly setting PCI-E v3.0 in BIOS was rendering system unbootable until CMOS was cleared. It seems v3 was either not supported by CPU at all or it didn't work in combination with my motherboard.
X79-based systems are already considered legacy since long ago and it is not very likely that someone will decide to build it these days, especially with a quite rare engineering sample CPU. In this case though, my recommendation is to avoid QAFF S-Spec CPU and choose many other options supported by the motherboard.
- Initial system boot and even reboot process could randomly freeze with a different number of BIOS beeps or motherboard boot status codes (Extreme-4M has a specific LED indicator for them). Probably the most common final code before freeze was 0x67 - CPU DXE initialization (CPU module specific). I believe it could have been RAM detection/initialization issues. Unfortunately, I couldn't find any pattern to reproduce the failure consistently.
- PCI-E graphics cards with v3.0 specification (possibly v2.0 as well) lead to the failure of the OS boot process into graphical environment (Windows 7, Gnome on Manjaro Linux, etc). Reducing PCI-E mode to version 1 in BIOS settings was partially solving the issue by stabilizing the boot process. In this case however, the system had an occasional performance degradation and/or random lockouts. I was using Radeon RX460 graphics card, but I found a MSI forum thread confirming the similar issue with different graphics cards (including AMD and Nvidia models).
The second problem was easier to identify since the problems started soon after I replaced older Radeon 2400PRO based graphics card with more modern Radeon RX460 one. Windows boot process locked out immediately on first reboot after AMD drivers were installed. Linux boot process froze as well on loading display server (X.Org). In both cases, the only way to continue was to reset the system. By default, BIOS was selecting PCI-E v2 for the graphics card. Reducing PCI-E to version 1 helped to load the desktop environment in Linux but system performance was unstable up to complete system lock out. Windows was still crashing regardless of the PCI-E mode set in BIOS. Explicitly setting PCI-E v3.0 in BIOS was rendering system unbootable until CMOS was cleared. It seems v3 was either not supported by CPU at all or it didn't work in combination with my motherboard.
X79-based systems are already considered legacy since long ago and it is not very likely that someone will decide to build it these days, especially with a quite rare engineering sample CPU. In this case though, my recommendation is to avoid QAFF S-Spec CPU and choose many other options supported by the motherboard.
