Dual CPU's showing in single-proc Dells

[JeffO93]

We just bought two new Dell computers:
Optiplex SX270 mini-formfactor
Precision 360
Both are Intel 2.4GHz P4, Intel boards, 800MHz bus.
Each has the new BIOS that allows me to boot off 64MB & 128MB USB sticks.

Thing is, these both have the same oddity - the BIOS reports one CPU. Windows thinks there's two. Device Manager, Task Manager, Winmsd, you-name-it. Windows is certain there are two CPUs. Device Manager says ACPI is "multiprocessor".

I'm guessing this is because of an architecture change. Could be the BIOS, the motherboard, the CPU,??? The computers are fast and operating without a problem.

Anyone else seen this with their new Dells or Intel boards?

p.s.
I was trying to post at Dell, but that's a joke! I wrote this entire post while waiting for the Dell logon to finish!

[DocPC]

We just bought two new Dell computers:
Optiplex SX270 mini-formfactor
Precision 360
Both are Intel 2.4GHz P4, Intel boards, 800MHz bus.
Each has the new BIOS that allows me to boot off 64MB & 128MB USB sticks.

Thing is, these both have the same oddity - the BIOS reports one CPU. Windows thinks there's two. Device Manager, Task Manager, Winmsd, you-name-it. Windows is certain there are two CPUs. Device Manager says ACPI is "multiprocessor".

I'm guessing this is because of an architecture change. Could be the BIOS, the motherboard, the CPU,??? The computers are fast and operating without a problem.

Anyone else seen this with their new Dells or Intel boards?

p.s.
I was trying to post at Dell, but that's a joke! I wrote this entire post while waiting for the Dell logon to finish!

It's called hyper-threading......The P4c CPU's will show 2 processes.

[JeffO93]

Strange. I've built dozens of P4 machines. None of them have had this dual-CPU behavior. I thought all P4s were hyper-threading. Since these are the only two that do this, I figured it had to be something else.

Does hyper-threading require add-on software?

I don't see any BIOS settings related to this. Every computer we've bought in the past year has been a P4 from Dell. My Gigabyte board at home has a P4. It reports one CPU. This is new behavior.

So if it's hyper-threading, and if it doesn't require software addons, then when going off the model # when purchasing the CPU, how do you tell which P4's have hyper-threading and which don't?

[DocPC]

P4's come in 3 flavors. A, B, and C. A is 400FSB and does not do HT. B is 533FSB and I think a couple do HT. C is 800FSB and I think most of them do HT.

Not totally sure what speeds do what, can't remember......getting senile.

EDIT: Actually, there are 4 kinds. I forgot the Socket 423........NONE of those do HT.

[confus-ed]

Not only do you need a hyperthreaded chip, but a chipset that supports it too, Hyperthreaded P4's fit in more chipsets than this list (below) but won't show as such unless its in one of these ...

Hyper-Threading Technology supported by the Intel® 850E, 845GE, 845PE, 845GV, 845G(2), 845E and 875P chipsets

We also think '865G, P, PE chipsets' too (thanks Doc)

(or that's what I found on their press release ... there might be some more !)

I'm having trouble too though figuring just which p4s are actually hyperthreaded, All the c's do I think & the b's from 2.4 onwards ? (If anyone turns up a 'definative' link, please post). There's also now those 'extreme' p4s which also do

As for how you tell, its dependant on the number on the chip ... Have a look at this pdf , with retail its easy though it says in big letters on the box

So Doc P4's now come in 5 flavours !

[DocPC]

Yup, forgot the Exteme Edition....

Your quote is missing the 865G, P, PE chipsets as supporting HT. We can add those in.

[JeffO93]

@DocPC, @Confus-ed, thanks both very much. That nails it down about as well as it can be.
I've grabbed the entire post and pdf and pasted it into a Word doc to distribute to the other techs. No one else here has seen this either.

[confus-ed]

Most welcome

[DocPC]