Hello,
I am still using an old PC with a EVGA-motherboard 132-yw-e178-ftw (EVGA force 780i SLI FTW) and Win10-64 (21H2 LTSC IoT). It was sold with an Intel Core2 E8400-CPU and 4 x DDR2-6400-2GB-RAM. The PC does for me what I want and so there is nor need for buying a newer PC (or using Win11).
But for use of VT-x (and a little bit of acceleration) I have replaced the CPU with an Intel Core2 Q9400.
After booting it works, but CPUZ reports only 1 Core and 1 Thread. In the BIOS (last version SZ17) I found in CPU-features the possibility to enable/disable the CPU-cores (0 to 3). Enabled was not surprisingly only Core 0. But after enabing Cores 1 to 3 the PC does not boot any more some secons after booting Win10 it stops and hangs and the circle is standing still. This also with enabled Cores 0 to 2. Only when enabling the Cores 0 to 1 (2 Cores) Win10 is booting. And like the number of enabled CPU-cores (2) CPUZ reports 2 Cores and 2 Threads only.
The CPU is o.k.; i have tested the Q9400 in another motherboard where it works w/o problems and CPUZ reports 4 Cores and 4 Threads.
So my question: What is the problem? Is there any other adjustment in the BIOS I need to adjust for 4 cores?

The issue becomes more an more strange.
I have tested also with a Q9300 (both - Q9400 and Q9300 - are working on other PC with other mainboard w/o problems and with 4 cores. The same result: Working only with the first two cores enabled, on other combinations ore 3 oder 4 cores it freezes after some secons of booting, sometimes also with 2 cores. The same with other OS like Linux and old Win10-64-installations (1709).
Then I erased the CMOS/BIOS-adjustments (power-off and clear-switch). When booting the first time (!) after this w/o access to the BIOS an old Win10-64-installation (1709) is starting. After rebooting or after access to the BIOS at first (also w/o changing anything and leaving w/o save) it freezes while booting, sometimes a little bit later. This default-BIOS-adjustments after clearing the CMOS are a little bit different reg. the CPU-features, but the main difference is that the "CPU Multiplier" is "Auto" instead a fixed value (e.g.8).
Waiting a while in power-off and starting again Windows is booting (21H2 and 1709) and stays some time working in idle; the temperatures of the cores are below 50° C (in other PC / with other mainboards the temp a above 50° C but w/o problems). But after some time or moving the mouse Windows freezes again.
What´s wrong with this EGVA-mainboard?