Keep in mind, older Pentium 4s are kinda hot and power hungry.
65nm Cedar Mill's (Pentium 4 6x1 series), are the best Pentium 4's (reduced temps and power draw).

Why Single Core ?
Just buy a Core 2 Duo.
OS will only use one core from it - true but, so what ?
It's not like they cost hundreds of dolars and if you ever decide to dual boot with Win XP, it will help A LOT with it's games.

I'm already planning a winxp standalone rig, mainly because of the ram limations between the os's and I don't know how to handle it on one machine, it would also require a motherboard that has one agp and one pcie slot or two pcie slots possibly.

Edit: just bought a celeron 450 for two bucks, I may just buy a few cups since there are all pretty cheap and run my own tests.

agent_x007 wrote:

OS will only use one core from it - true but, so what ?

If this^ is true, and Win98 can be installed on a machine with a multi-core CPU and will "ignore" the extra cores without errors (since the 775i65G R3.0 manual doesn't list a BIOS option to disable extra cores), then yes, you should find a C2D-based CPU. The faster ones will outrun any P4 in single-core performance and will also run cooler.

In the case of the 775i65G R3.0, the fastest would be the Pentium E5800 @ 3.2GHz. (The CPU support list has 1066MHz FSB processors as well but these require an AGP card to be installed + CL2.5 DDR-400 memory; if you have both of these, you could use a Pentium E6800. The list also has a Pentium E5900, but I don't think these are easy to find.)
EDIT: spelling

as far as I know windows 98 simply ignores the other cores and works happily;

the mentioned e5800 is super cheap and should be pretty fast at 3.2GHz,

E5800 is the best CPU you can put onto it. Make sure it's the R3.0 version of the motherboard you have. It has to have a black PCB. It's the best CPU with official 98SE support. Don't go with Q6600, even though it is supported, the 1066 FSB causes severe boot times increase, and lower DDR memory performance.

MrMateczko wrote:

E5800 is the best CPU you can put onto it. Make sure it's the R3.0 version of the motherboard you have. It has to have a black PCB. It's the best CPU with official 98SE support. Don't go with Q6600, even though it is supported, the 1066 FSB causes severe boot times increase, and lower DDR memory performance.

how come an increased fsb rate slows down boot and memory?

yep, the E5800 has a 800mhz fsb ?

E5800 has 800Mhz FSB, so full motherboard performance on it, no hacking. Get it.
Here's full list of CPU supported by 775i65G R3.0:
http://www.asrock.com/mb/Intel/775i65G%20R3.0 … dex.asp?cat=CPU

ASRock's implementation of 1066 FSB support on the 775i65G R3.0 is kinda hacked. They make the DDR run at the slowest 133Mhz, with no option to change that. They do other hacking with other base clocks as well during the boot up, that's why it's taking so long.
It's not worth it, you want the system to boot up fast, not slow.
Bear in mind, I'm telling from what I read from other people on the internet, I do not have this motherboard, nor a 1066 FSB CPU. For more info, try looking up people who has the same motherboard, and a 1066 FSB CPU.