Hyperthreading on the P4 Northwood architecture was "OK" at best, and somewhat detrimental at it's worst. There wasn't enough register space to fully utilize it properly, nor was there enough cache to make it efficient in a lot of cases.
The P4 Prescott line doubled both the register space and cache sizes to alleviate those issues, but even then it wasn't much better than "OK" -- it was just "less bad" in bad situations.
As a completely seperate aside, I once owned an Albatron PX845PE Pro IIs motherboard way back in the day. I had upgraded to an 865 chipset board and left the 845 in it's original box buried in my closed for years. Eventually I found it again and was preparing to sell it to a buddy -- but wanted to test it first. The only processor I had to test with at the time was a 2.4C / 800FSB part, so I dropped it in there...
I had the same initial experience as Rude: it booted at 1.2Ghz and with HT enabled. But here's where it got cool: I could overclock that 845 board all the way to 828FSB (207Mhz) with full operation of all the devices on it -- firewire, USB, sound, SATA and PATA ports, AGP socket, even the memory chips were doing 550Mhz (207 x 2.66; I had some PC4200 ram laying around).
For such a decrepit old chipset, that board kicked a lot of ass with an 800FSB processor in it
Sold the board for $50...
The P4 Prescott line doubled both the register space and cache sizes to alleviate those issues, but even then it wasn't much better than "OK" -- it was just "less bad" in bad situations.
As a completely seperate aside, I once owned an Albatron PX845PE Pro IIs motherboard way back in the day. I had upgraded to an 865 chipset board and left the 845 in it's original box buried in my closed for years. Eventually I found it again and was preparing to sell it to a buddy -- but wanted to test it first. The only processor I had to test with at the time was a 2.4C / 800FSB part, so I dropped it in there...
I had the same initial experience as Rude: it booted at 1.2Ghz and with HT enabled. But here's where it got cool: I could overclock that 845 board all the way to 828FSB (207Mhz) with full operation of all the devices on it -- firewire, USB, sound, SATA and PATA ports, AGP socket, even the memory chips were doing 550Mhz (207 x 2.66; I had some PC4200 ram laying around).
For such a decrepit old chipset, that board kicked a lot of ass with an 800FSB processor in it
Sold the board for $50...