Magic lemons - I/O letters #36

IOOTM: Asymmetrical multiprocessing
A few years ago, I brought a Gigabyte GA-6VXD7 P3 Dual Motherboard. I brought a Pentium 3 866MHz as well at the time. I set up the PC as a server for these last several years, but couldn't find a good price for a second CPU. A friend of mine recently gave me a Pentium III 800EB processor, though. Is it possible to lower the multiplier on my 866MHz CPU to run at 800MHz, and use the 800EB processor as my second CPU? Both are 133MHz FSB CPUs, but I know dual CPU can only be used with identical CPUs. The motherboard only has one DIP switch for the multiplier. Also, if this can be done, will the performance difference be great? I mainly use the machine to host Apache and MySQL on Win2000.
King Lam

A: First the bad news: No, you can't change the multiplier of either P-III, unless they're non-retail engineering samples. Every other Intel CPU since before the first P-IIIs has a locked multiplier.

Now the good news: It doesn't matter. Yes, SMP stands for Symmetric Multiprocessing, and that suggests that the CPUs ought to be the same speed, and indeed they usually are. But it's actually OK if they're not. Just plug the second CPU in, and it should work with the first one. Windows shouldn't miss a beat. Note that many motherboards don't give you much in the way of independent settings for the two CPUs -- maybe separate voltage settings, but that's it -- so mixing processors that want different FSB speeds can be a problem. You're not doing that, though, so you'll probably be fine. Whether you'll notice a difference is another question. A web and database box like yours certainly can benefit from more processor power, but only if it's actually loaded heavily enough. If it's not floating around 100 percent CPU utilisation very often at the moment, then the second processor won't do much for it.

PATA plus SATA
I have an MSI K7N2G-ILSR motherboard and two WD 120GB hard drives plugged into IDE.
I was wondering if I can buy a SATA hard drive and use it as well on top of the existing two?
Jordan Xu

A: Yes. The ILSR version of the K7N2G runs its two SATA ports, and its third PATA port, from a separate Promise 20376 controller chip. Some motherboards allow you to use a couple of SATA ports only if you don't use one PATA port, but the K7N2G-ILSR lets you use all of the connectors simultaneously, for a maximum of six PATA devices and two SATA devices at once.

Universal 1394 Bus
I was recently given a USB2 drive enclosure, which is great, except that my Inspiron 8200 laptop only has USB1.1 onboard. It does have FireWire though, so I thought that I'd be able to get a converter to run the USB2 drive off the FireWire port. But, after a long Google and online computer store search, it would seem that no such USB/FireWire converter exists. Is there a technical/legal reason for this, or did I just not look hard enough?
Dan Sketcher

A: I don't think it's technically impossible to translate FireWire into USB, though the fact that high speed USB 2.0 has a higher (theoretical) data rate than FireWire (480Mb/s versus 400Mb/s) could be a problem. The main reason why nobody's bothered making such a device, though, is that there are few situations when you can't just install a USB 2.0 adaptor in the computer that needs one. In your case, if your laptop's got room for another Type II PCMCIA card (the Inspiron 8200 can accept two Type II cards), you shouldn't have any trouble finding a USB 2.0 adaptor for it. Expect to pay $75 or less for a perfectly good off-brand card.

It's a RAID!
I was reading PC Authority (every Atomican's second-favourite mag) and noticed that the Seagate Barracuda ST3160023AS 160GB hard drive cost $264, and the Western Digital Caviar WD2500JD 250GB hard drive cost $589. I was thinking -- why buy the Western Digital when you can buy two Seagates and a RAID controller, run them in a RAID 0 array, and get more storage plus the benefits of striping? I know what you're going to say – 'Why not get two 250GB hard drives and run them in a RAID array?' An excellent point with just two problems.
1. Who has over $1K to spend on hard drives?
2. Who needs half a terabyte of hard drive space (OK, maybe 400GB after formatting.)
Don't know how to set up a RAID array? That's fine, get your sister's boyfriend's ex-flat-mate's cousin's best friend to set one up - or pay me to do it!
Ben Halpin

A: Sure, you can RAID a couple of cheaper drives to get more capacity than a high-end one offers. You can probably even boot from the array. However, RAID 0 is not really RAID (Redundant Array of Inexpensive, or Independent, Disks), because it has no data redundancy; there's zero fault tolerance. If any drive in a RAID 0 array fails, the array is toast and you can't do anything but reformat the surviving drives.

For this reason, bare RAID 0 is generally only used for high-speed storage of intermediate data, like video being edited.

You're not talking about a 16 drive array, of course - just two. Only two times the already pretty low failure probability of a commodity drive isn't especially terrifying. You can just take the risk and probably be fine, especially if you make regular backups (which you should do anyway), and retire the drives to less important duty when they're a couple of years old (commodity hard drives aren't built to last).

If you want fault tolerance, though, you either have to go to RAID 0+1 (a striped array mirrored to another striped array, requiring twice as many disks for the same capacity) or RAID 5 (a striped array with parity information also striped across the drives, requiring 1.5 times as many disks for the same capacity). A three drive RAID 5 array can survive the death of any one drive; a four drive RAID 0+1 array can also endure any one drive failure and also survive a second, provided that drive wasn't mirroring the first one that failed.

Cheap RAID controllers pretty much all support 0+1. You generally have to pay a bit more to get RAID 5, or do it in software with the Server Windows variants, or Linux or FreeBSD or what have you, but then you can't boot from the array. Either way, of course, you're not getting that great a dollars-per-gigabyte bargain any more.

Fan-a-rama
I have recently purchased an 800MHz FSB P4 2.4GHz and an ASUS P4P800, which I have overclocked to 3GHz without any problem. However, when I had it up to 3.3 GHz, it tended to freeze when under load.

I have since purchased and installed two case fans to assist (and to provide blueness, aaah). However these have dramatically increased the noise (I have a quiet power supply). The Intel cooler is very quiet, especially while it is below 50°, as the motherboard drops the speed while the temperature is low.

Can I connect the case fans to the same monitoring and speed control as the CPU cooler, so that while the CPU is cool all three fans run slowly, and increase when required?

If not, can you suggest another way to automatically adjust the case fan speed based on the temperature?
David Walters

A: Maybe, although you're unlikely to be able to find a pre-wired adaptor that'll let you do it.

What you want to do is connect the positive and ground wires for each of the case fans (probably red and black, respectively) to the positive and ground wires of the CPU cooler fan, so all three fans are wired

• Purchase your copy now - only $8.95 including postage
• Subscribe to our digital version - only $49.95 a year