test your 3ghz at 533fsb (2ghz). If the speed is still ok for your other games you can swap to the dual xeon and benefit in games that support dual core.
If it is too slow for your single thread games they probably will not run much better with the xeons.

The athlon should be a tiny bit faster in games compared to the 3ghz and should be able to overclock to really get some more speed, i think it is the best match for the 3850.

Dualcores can be had really cheap these days, i would go for that.... if you want to play 2010 games or newer a fast or overclocked core2duo and at least a 8800gt/hd4870 pci-e is a must imho, and even those can have a hard time.
In early 2010 the top dog was the gtx480/hd5870.

Bleah, seems I don't have a working PSU with the right dual-fan connector for the Xeon board, and I was too lazy to make one up. And the AMD is an Athlon XP, not 64... So I'm still using the P4/3.0.

...which, as it turns out, is totally 100% awesome with the new video card. The 'unsigned' driver was a bit finicky to install but once I figured that out it was solid. Everything that already ran fine got a nice speed boost and the new DX9.0c/PS3.0 stuff I wanted to try goes really well. Nitronic Rush is smooth like candy at 60FPS with all the detail options on (albeit at 640x480!) Fez is a tiny bit pokey but I already 200%ed it on my Macbook so no big deal. Totally playable though. I don't have a copy of NFS 2010 yet but I have no reason to think it would be too slow.

In fact this is probably the most powerful gaming rig I've ever had. 😉 Makes me wonder what else I've missed in the last few years that I could actually play on it.

I'll save the dual Xeon board for a Linux box, probably with an Nvidia card so I don't have to deal with xorg-radeon... Seems appropriate.

AGAIN with this thing ...

The claimed "Core2 Duo" system I picked up at a garage sale last weekend turned out to be another Socket 478 board (Abit IC7-MAX3) with another P4/3.0 HT. So that's pointless. (It came in a MONSTER Thermaltake gaming case, seriously you could start hurricanes with all the fans in this thing! The case alone was worth the price I paid, plus the nice PSU, GeForce card & DDR2 RAM so I'm not upset.)

Gonna stick with the 8IPE1000-G for now, I don't feel like messing with it anymore.

What's the best CPU I could drop into a socket 478? I've seen conflicting info on whether you could get a Core2 Duo or Pentium-Dual Core in that form factor (e.g. this "socket 478" Core2 Duo on Ebay.) Are all 478 chips compatible?

If I dumped a presumably-compatible dual core CPU in, it wouldn't do something stupid like operate on one core only would it? I don't think multi-core was a think when this board was made.

Sorry, it's been a LONG time since I've messed with building my own machines. Have some catching up to do.

There are S775 boards with AGP. I think these are as good as it gets.

Then there are also S775 PCIe boards, and they take the late Pentium 4 chips like Cedar Mill.

IMO be happy with the 3000/512/800 Pentium 4. If what you're doing needs more performance, then it's time to move to something newer 😀

Under XP, dual core is supported and many games benefit from it. Not a massive amount, but it's measurable in benchmarks. However my tests were on a much newer S1155 platform, so this might not apply to your situation.

There are no dual cores for 478. The fastest processor made was the 3.4ghz Pentium 4 Extreme, the second best and more common would be a 3.4ghz Prescott. Although you could overclock your existing 3.0ghz chip to 3.4ghz no problem. The P4 is "kinda" a dual core in the fact that it has Hyperthreading, which kinda acts like a virtual second core.