The Old Joel on Software Forum: Part 3 (of 5)

HT vs. Dual CPUs

I've been contemplating a new motherboard with dual Xeons (keeping the rest of my hardware, of course). After some pretty extensive research, it seems like dual CPUs for workstation use are not very effective. Dual Xeons w/ the 533 FSB compared to a single P4 w/ the 800 FSB is about dead heat. It seems as though the cache advantage of the Xeons is lost because of the slower FSB and slower RAM.

I found this pretty surprising. Clearly, a $150 mobo and a $250 chip is a much better deal than a $300 mobo and a couple $300 chips and $100 Xeon-compatible power supply.

Anybody got any thoughts?

Brad Wilson (dotnetguy.techieswithcats.com)
Thursday, October 2, 2003

http://cr.yp.to/hardware/advice.html

Rob Mayoff
Thursday, October 2, 2003

I don't do Athlons. My life is too short.

Brad Wilson (dotnetguy.techieswithcats.com)
Thursday, October 2, 2003

I would go the single CPU route.

James Ladd
Friday, October 3, 2003

I have used many AMD CPUs, for a LOT of time, and on A LOT of computers.

I have used:

- Athlon XP
- Duron
- K6

They are all excellent - rock-solid and stable.

Of course, in order for them to be stable - you have to use a good motherboard and RAM, but this is the same as for using an Intel CPU.

a long time Athlon user
Friday, October 3, 2003

And Brad, please stop spreading FUD about Athlons and AMD.

You are probably talking about something you know nothing about.

a long time Athlon user
Friday, October 3, 2003

Brad's had bad experiences with Athlons and certain motherboards and is just relating that, as is his right to do so. Your mileage may vary, I know that mine does as I've been using an Athlon XP for quite a while now and it's never missed a beat.

Such is the way of the world.

John Topley (www.johntopley.com)
Friday, October 3, 2003

AMD FUD'd themselves in the foot by not honoring the warranty on CPU's cracked by their poor design.

"Dual Xeons w/ the 533 FSB compared to a single P4 w/ the 800 FSB is about dead heat"

Cite? What kind of benchmark? Remember, dual CPU's is not about how fast a *single* task runs - it's about responsiveness of the OS while you have multiple tasks running.

Philo

Philo
Friday, October 3, 2003

I should've saved all the links... I was all over the web yesterday, digging through articles and benchmarks.

Basically, it seemed like most of what I read validated what I'd already thought: make sure you have plenty of RAM, and a fast disk, preferably Serial ATA or SCSI.

On the CPU intensive benchmarks, designed to test multiple CPUs, adding the second Xeon only added about 15-20%. The differences in having a system with an 800MHz FSB and 400MHz RAM over 533/333 was significant enough to more or less nullify this double CPU advantage. Now, if there were 800 FSB Xeons, I'm sure the story would be different...

~~~

As for "spreading AMD FUD", I'm not telling anybody else not to use AMD. I've just had years of being burned by their systems, and wasting time on them, so that I'll never do it any more. I'm glad others can get satisfaction from them. Plenty of my friends use them with success. But for whatever reason, they have been nothing but hell for me from a stability standpoint. I simply refuse to spend any more time chasing the ghost.

Brad Wilson (dotnetguy.techieswithcats.com)
Friday, October 3, 2003

Oh, and in case you think I'm just making things up about Athlons... I've tried quite a few motherboard/CPU combos. The first set I had was pretty good: Asus (Via) with Athlon 900 w/ the 100MHz FSB.

As soon as I switched over to a system with the 133MHz FSB, that was when stability ended for me. Motherboards primarily using Via chipsets, even AMD chipsets (the supposedly rock solid 761), using Athlons and Athlon XPs. Using PC-100, PC-133, DDR-266. Always using high quality parts, including name brand RAM (Crucial), major manufacturer motherboards (Asus, Abit, Gigabyte), and video cards from ATI and nVidia, sound cards from Creative and others.

No matter what combination of parts I used, there wasn't a single one of them was stable enough for a day-long gaming session.

Anyway, back to the original point, if you please.

Brad Wilson (dotnetguy.techieswithcats.com)
Friday, October 3, 2003

"On the CPU intensive benchmarks, designed to test multiple CPUs, adding the second Xeon only added about 15-20%"

On a single CPU machine, start a CPU-intensive task (compiling, IDE drive access, image rendering, etc)

Now minimize that window. Go check your email.

In *my* experience, it's click, pause, menu, mouse down, pause, get menu highlight. Click, pause, wait, pause, action starts... Type and watch the keyboard buffer fill before you see anything on the screen. Etc, etc, etc.

With a dual proc system you don't see any of that. Everything is always responsive. I've used a LOT of boxes, from corporate borgware to homebuilt stuff, and that's what I keep seeing.

Philo

Philo
Friday, October 3, 2003

I must be weird, because I just don't see that kind of behavior on my desktop. It's a non-HT P4 system with gobs of RAM and very fast disks, though.

Honestly, I haven't seen that kind of "I/O throttles the system" behavior since 9x, with the exception of the small time window before the system is fully booted. Am I alone?

Brad Wilson (dotnetguy.techieswithcats.com)
Friday, October 3, 2003

Brad,

Philo was suggesting a CPU intensive task, not an IO intensive one. Run something that pushes your CPU over 85% or so. With a dual proc you could restrict that app to one processor if you wanted or just allow it to spread itself over them all. More than one CPU makes a difference in this situation even if you dont tweak particular processes.

Len Holgate (www.lenholgate.com)
Friday, October 3, 2003

I do have a computationally expensive app that I tested with, and I still don't see it. Perhaps the app in question is doing its computation on a low priority thread (it's not something I wrote, it's an audio editor, and applying the audio effects to 30 minute long audio track generally takes quite some time with the CPU pegged at 100%).

Brad Wilson (dotnetguy.techieswithcats.com)
Friday, October 3, 2003

For the folks with the dual Xeons, did you buy or build these youselves.? I 'm looking into purchasing new development workstations, and would like to buy dual boxes. Any links to site where I could purchase machines or parts. I'm tempted to go with the usual Dell or HP Compaq, but I would love to find someone cheaper or buid them myself.

--Garett

Garett Chang
Friday, October 3, 2003

i built a dual P3-800 back in dec of 2000, but my current dual Xeon-2.0GHz is a Dell Precision 450.

nathan
Friday, October 3, 2003

After a lot of heavy shopping, this is what's on my favorites list:
http://www.arsenalpc.com/ars/systems/int-tower-serv/tower-dual-xeon.html

It's the only place I've found that meets these criteria:
1) Dual Xeons
2) SCSI
3) Decent sound card
4) Decent video card
5) Decent price

The problem, in general, is finding (1) at all, then finding 1 & 2 with 3 & 4 - most places that do actually offer dual Xeons think they're only good for servers so you can only get the "on the board" video and sound.

And of course if you get 1-4, you're generally spending a mint - at Alienware (before they dropped SCSI) a system was running $6k. A better system at Arsenal is $3k.

But let me be absolutely clear - I've been drooling, but I have not bought from them yet, so I can't comment on service or support. :-/

Philo

Philo
Friday, October 3, 2003