In Intel-land, I would say LGA775, early C2D (965/975 chipsets), late Pentium 4/Pentium D, DDR2. I had a 7900G...T with my C2D E6600, and I think that came out a few months after the GTX (which launched in March 2006). Definitely not 1366/AM2 - that's years later...

(That being said, if I was in your shoes and I didn't already have the mobo/CPU, I would probably 'cheat' and get something that supports 45nm C2Ds...)

Realistically, the 'very decent' build in March 2006 was an AMD X2 3800+ on 939, or if you were made out of money, one of the faster AMDs, but the 3800+ was the sweet spot. It was a dark era for Intel fans, although the rumours of something magical named Conroe on the way kept us out of the computer store and hoping for some redemption...

Now, my understanding is that those early AMD 64-bit chips are missing some instructions required for newer Windows OSes, so if you wanted to play with anything newer than XP/Vista, that might not be your best bet. The 45nm C2Ds, while period-incorrect, will unsupportedly boot Windows 11 at least for now, although that's supposed to break in a few months.

I still remember this era somewhat vividly as I was a teenager in high school and had just started to get into computers. For most of 2005-2006, socket 939 AMDs and late socket 478 Intel were the hardware of the era. The dream machines were pretty much all AMD Athlon 64 X2 and FX stuff. I don't remember if Pentium D was out yet at this time... but even when that came out, it was still outperformed by the AMD X2 chips.

Those s939 X2 CPUs are kinda of getting pricey now, though, so I don't know if I can recommend them. But the single core chips are still a dime-a-dozen, more or less. Depending on what games you want to play, an OC'ed A64 3200+ could still give those GeForce 7800 / 7900 GTX cards a go for their money. Most games from 2005-2006 were single-core -based, so you'd probably see better results with a faster single core CPU than a slower dual core one.

VivienM wrote on 2024-04-18, 23:09:

Now, my understanding is that those early AMD 64-bit chips are missing some instructions required for newer Windows OSes, so if you wanted to play with anything newer than XP/Vista, that might not be your best bet.

No, you can do up to Windows 7 fine.
Not sure about 8/8.1 or 10... though I think even those will work on an old CPU like that.
IIRC, SSE3 instructions go as far back as socket 754. On the Intel side, the only socket 478 CPUs that have SSE3 are the Prescott. Northwood is SSE2, which if I remember is what's needed for 10 (and possibly 8/8.1)... though I also remember seeing a workaround for that too.

momaka wrote on 2024-04-19, 00:33:

No, you can do up to Windows 7 fine. Not sure about 8/8.1 or 10... though I think even those will work on an old CPU like that. […]
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VivienM wrote on 2024-04-18, 23:09:

Now, my understanding is that those early AMD 64-bit chips are missing some instructions required for newer Windows OSes, so if you wanted to play with anything newer than XP/Vista, that might not be your best bet.

No, you can do up to Windows 7 fine.
Not sure about 8/8.1 or 10... though I think even those will work on an old CPU like that.
IIRC, SSE3 instructions go as far back as socket 754. On the Intel side, the only socket 478 CPUs that have SSE3 are the Prescott. Northwood is SSE2, which if I remember is what's needed for 10 (and possibly 8/8.1)... though I also remember seeing a workaround for that too.

On 32-bit or 64-bit?

I don't think any 64-bit 478 chips were ever made. But I think you're right, 32-bit versions of 7/8.1/10 should be fine, if you can live with the RAM limitations.

On 64-bit, I believe at least 8.1 requires instructions that the ~2005-6 939 Athlons don't have. I thouuuught I had read something at some point suggesting later 7 patches had also added a requirement for those instructions.

In early 2006 I upgraded my socket 939 system from single core A64 3000 to dual core Opteron 165, which I promptly overclocked to 2.5ghz. At that time dual core A64 were all the rage.

OK I did a quick search.
Apparently the old s939 CPUs should officially support up to Windows 8.
8.1 is a no go as it requires some instruction that most s939 CPUs lack (except for the late ones.) I don't remember if there was a workaround for that or not. For 32-bit Win 8.1 and 10, there is, and those can be made to work OK.

VivienM wrote on 2024-04-19, 00:46:

I don't think any 64-bit 478 chips were ever made.

There is one... actually two!
SL7QB and SL7Q8
They were custom orders for IBM. More info can be found here:
https://www.cpushack.com/2019/10/01/the-story … m-4-64-bit-cpu/

VivienM wrote on 2024-04-19, 00:46:

On 64-bit, I believe at least 8.1 requires instructions that the ~2005-6 939 Athlons don't have.

That seems correct.

pixel_workbench wrote on 2024-04-19, 00:58:

In early 2006 I upgraded my socket 939 system from single core A64 3000 to dual core Opteron 165, which I promptly overclocked to 2.5ghz. At that time dual core A64 were all the rage.

Yup, Opterons and X2's were indeed what I remember everyone was running on gaming forums back then... at least until Core 2 came out.