After pondering this is suspect it may be down to the 960 (Presler) having VMX (Virtual Machine Extension) support and this being absent on the 840 (Smithfield).

red-ray wrote on 2020-01-19, 15:14:

After pondering this is suspect it may be down to the 960 (Presler) having VMX (Virtual Machine Extension) support and this being absent on the 840 (Smithfield).

No, I don't think that's the reason.

https://en.wikipedia.org/wiki/X86-64

release date of ee 840: May 1st
Pentium Extreme Edition 840 SL8FK 3.2 GHz 2 × 1 MB 800 MT/s 16x 1.2 - 1.4 V 130 W LGA 775 May 1, 2005 HH80551PG0882MM $999

from Wikipedia:
"
Early AMD64 and Intel 64 CPUs lacked LAHF and SAHF instructions in 64-bit mode. AMD introduced these instructions (also in 64-bit mode) with their Athlon 64, Opteron and Turion 64 revision D processors in March 2005[46][47][48] while Intel introduced the instructions with the Pentium 4 G1 stepping in December 2005. The 64-bit version of Windows 8.1 requires this feature.[45]
"

So I would say it is missing LAHF and SAHF instructions.

So last working 64 bit windows for this cpu is Windows7. Windows 8.1 and Windows 10 won't run on this cpu.

CoffeeOne wrote on 2020-01-19, 17:12:

So I would say it is missing LAHF and SAHF instructions.

So last working 64 bit windows for this cpu is Windows7. Windows 8.1 and Windows 10 won't run on this cpu.

Ahh so only the 32bit Win8.1 and 10 will work. Wonder what would happen if Win10 was installed from scratch ? Would it actually try to install or abort saying system does meet Win10 requirements ??? .. hmmm

Horun wrote on 2020-01-19, 20:27:

CoffeeOne wrote on 2020-01-19, 17:12:

So I would say it is missing LAHF and SAHF instructions.

So last working 64 bit windows for this cpu is Windows7. Windows 8.1 and Windows 10 won't run on this cpu.

Ahh so only the 32bit Win8.1 and 10 will work. Wonder what would happen if Win10 was installed from scratch ? Would it actually try to install or abort saying system does meet Win10 requirements ??? .. hmmm

Actually I had the same problem with an Athlon 64 PC (with a Opteron 170 cpu). Windows 7 64 bit no problem, but Windows 10 64bit did not run, the Opteron is missing the CMPXCHG16b instruction, aaaahhhhh
So I ended up with installing Windows 7 32bit, and upgrading it to Windows 10 32bit.
One of the slowest Windows 10 Pcs ever. It has 2GB RAM though, but no SSD, windows 10 is really sluggish without ssd.

Thank you for the insight and yes, I bet it's slow. I find the Pentium D 940 system slow and that does have an SSD and now has 8GB as I just found 4 x 2GB in a box. It least it's not my main system.

I just found a Xeon X5450, so I will give that a go once I get a https://www.ebay.co.uk/itm/153550883988.

red-ray wrote on 2020-01-19, 21:01:

Thank you for the insight and yes, I bet it's slow. I find the Pentium D 940 system slow and that does have an SSD and now has 8GB as I just found 4 x 2GB in a box. It least it's not my main system.

I just found a Xeon X5450, so I will give that a go one I get a https://www.ebay.co.uk/itm/153550883988.

You might need a modified - unofficial bios for that cpu. But you checked that already I guess.

CoffeeOne wrote on 2020-01-19, 21:07:

You might need a modified - unofficial bios for that cpu. But you checked that already I guess.

I have done my best to check and as the BIOS contains the 0001067A microcode it should work OK, but given Flags is 11 it's not for LGA771 Xeon which as no big deal as Windows will load it.

The LGA771 to LGA775 adapter just arrived and worked like a charm. I can now boot both Windows 10 and Windows 7. In both cases the µCode was loaded by Windows (it's not in the BIOS) with Windows 10 having a later revision.

The unexpected thing is the memory data rate is 833 MHz rather than 800 MHz which I think is down to P965 chipset limitations.