Dual CPU? A word of warning

[neil wilkes]

If you are considering taking the plunge and setting up your own home built Dual Xeon system, there are 2 things just happened to me I thought I would share here to stop anyone else getting caught the same way.

1/. This may sound obvious, but make sure that the CPU's are matched. Right down to from the same batch, or else despite being the same make, clock frequency or multipliers, your PC will only be running in UniProcessor mode.
Even if BIOS is showing 2 CPU, and Windows XP is showing 2 CPU, unless the numbers are exactly the same you will not be in MultiProcessor mode. I found this one out the hard way. Bought 2 Xeon, not the same batch, but everything else was the same. BIOS showed 2 - no problem. Then my ASUS PC-DL Deluxe mobo hit an F1 stop error - and told me the CPU's were mismatched and only to proceed if I was certain all was correct. I called for advice (No names to protect the guilty) and was tols that once Windows was installed the problem would go away. It didn't. I then called ASUS, who told me for a PC to be true multiprocessor, the CPU have to be from the same batch or it will work, but not properly. Intel confirmed this too.
The CPU supplier exchanged the 2 chips for a new set - same batch this time - all is well.

2/. Do not trust the fans in the CPU boxes. The supplied Intel Xeon 3.06 fans/heatsink arrangement is a plastic "tunnel" screwed to the motherboard, a retainer clipped onto this - loosely - and the fan clips onto this. The noise when 2 of these rev up is nothing short of Alarming!
One visit to QuietPC later, 2 radial Xeon coolers/fans, 2 silent case fans. Another £100, but worth it - I hope. Should be delivered tomorrow.

But seriously - always make sure that the chips are a matched pair, as if they are not it will look like you have a dual CPU syste, but in reality it will only be a uniprocessor system with none of the adbantages you should have.

 

[JonUrban]

Neil,

I had the same problems with the fans. The Intel fans are HUGE! I could not fit them on my motherboard. I called SuperMicro (who makes my MB), and they sold me "optional" fans. The Intel fans sit in their original boxes, waiting for a "someday" trip to the dump.

I did not have trouble matching the XEONs, as I bought them both at the same time from the same vendor. They must have matched them for me.

 

[neil wilkes]

It's not that the intel fans are huge - they are very deep & narrow - and so noisy!!
Oh well - hopefully it will be today that UPS bring the new ones.

I do hope so - Got Chrome 2 & WaveLab in boxes ready to go!

 

[Scottmoose]

All words above are those of wisdom -I agree 100% from my own experiance with multi-prossessing setups.
Couple of general things to add for anyone out there thinking about going along this route, but who hasn't had much opportunity to find out much about them.
1) Be wary of dual AMD setups (Personally, I like AMD CPUs, but not all software does. Usually no problems, but these's always the off-chance).
2) Remember that they cost a bomb, and having twin processors does not automatically mean you get twice the grunt -nothing like it in fact: I believe the average is between six and thirty percent gains depending on the software being used.
3) If you're running MS products, you'll need either Windoze 2000 or Win. XP Pro. (The home edition won't do) so there goes another Lot of Money.
4) To get the true best performance out of a dual setup, you need A Lot Of RAM. Minimum 512 mb (and we're really scraping the bottom here), more like over a gig. More cash.
5) As above posts: you need huge amounts of cooling; which means big, heavy and costly heatsinks, fans and a very large case with it's own fans (put one of these setups into a smallish case and see how far you get). Some suggest leaving the shell of the case off, but in a domestic environment, this is a Very Bad Idea.
6) Noise. Big fans + Large numbers of them + Outsized powersupply for all of the hardware = one very noisy PC churning out RFI. Unless again, you spend another Lot Of Money.
7) RAID array. Or SCSI. Almost a necessity, like the RAM, to get the best performcance out of it, and don't even think of skimping on the quality.

Is it worth it? Depends on what you want to use your PC for. 'Ordinary' use? Forget it. Not worth the effort. Pain in neck and wallet for no discernable gain. Occasional heavy processing? Possible gains, but if you aren't running intensive software all the time, the law of diminishing returns kicks in. Give it some thought. If you aren't feeling very rich, I wouldn't bother.
Constant, heavy processing -go for it. The gains in time you'll see will be significant.
I used to have an AMI Goliath motherboard with 4 Pentium Pro (remember them) 180 CPUs mounted (grin). I rescued it from a skip back in '99 after an IT firm junked it. In fact, I think it's still in the loft somewhere. Must've cost a bomb when new, but it was limited in real applications -NT server was a necessity for example (not surprising, that was what it was designed for). I eventually had to go back to a single processor machine that was a little more modern, and a lot more practical. Still, fun whilst it lasted -my regular machine at the time was a P166!

 

[neil wilkes]

I am finding out all about the enormous cooling troubles as I type this.
Current solution - Sides off the full tower, muslin cover instead. 7" domestic fan blowing directly into the mobo area. Zalman coolers/fans on the CPU's, 2 case fans - and I am considering HDD cooling from QuietPC.com as it is the heat on the HDD that is bothering me.
Is it worth it?
Emphatically YES! The power of this beast is simply enormous. An example is the PristineSpace Convolution Reverb Plugin from Voxengo - took 35-40% in idle mode on my previous Dual PIII 1.4 Tualatin rig.
In idle mode on this beast - 1.5%.
So to me, as I do a lot of multichannel mixing, it is very much worth it.

I will find the solution to all the heat. And when I do, I will post it here.

 

[JonUrban]

Maybe you need a bigger tower. Here is the one I use. It has a place for a ton of cooling, and space for a huge MB and 10 bays.

http://www.pcpowerandcooling.com/products/enclosures/professional/pro_towers/index.htmhttp://www.pcpowerandcooling.com/products/enclosures/index.htm

 

[neil wilkes]

Not much bigger than the current one.
Seem to have the cooling all sorted out now. Took off the steel sides, replaced with muslin cloth, and added a 7" desk fan in slow mode blowing directly onto the Zalman coolers. The airflow now goes all round the lot, and the temp has dropped significantly.

Shakedown time.....