Atomic I/O letters column #33
Originally published in Atomic: Maximum Power Computing Reprinted here May 2004. Last modified 16-Jan-2015.
Asymmetrical multiprocessing
A few years ago, I brought a Gigabyte GA-6VXD7 dual-P3 motherboard. I brought a Pentium III 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
One of these CPUs need not be like the other.
Answer:
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% CPU utilisation very often at the moment, then the second processor won't do much for it.
Note that after adding another processor to a Win2000 machine, you'll need to update its Hardware Abstraction Layer in order for the second CPU to do anything. You can do this without reinstalling, though.
PATA plus SATA
I have a 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
Answer:
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.
With the standard BIOS version you can only run five PATA devices and two SATA devices at once (only one PATA and two SATA drives through the Promise controller; still quite enough for your purposes), but this BIOS apparently solves that problem and lets you go all the way to eight drives.
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?
[yet another] Dan
Answer:
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 400 (480 versus 400 megabits per second) could be a problem.
I think 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 adapter
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 adapter for it. Expect to pay $AU75 or less for a perfectly good off-brand card.
(Close But No Cigar Department: This, which goes the wrong way.)
It's a RAID!
I was reading PC Authority (every Atomican's second-favourite mag) and noticed that the Seagate Barracuda ST3160023AS 160Gb hard drives cost about 45% as much as Western Digital Caviar WD2500JD 250Gb drives. 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. I don't have that much 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
Answer:
Sure, you can RAID a couple of cheaper drives to get more capacity than
a high-end one offers. You can probably even boot a PC from the array, these
days. 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 not-too-old 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 only one extra drive for the same capacity; three drives give the capacity of two, four drives give the capacity of three...). A 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 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 3.3GHz, it tended to freeze when under load (playing UT).
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 degrees, 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 below 50 degrees, 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
Answer:
You might be able to set the fans up the way you want, though you're unlikely
to be able to find a pre-wired adapter 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 in parallel. Only one fan's tachometer wire (assuming they all have them; tacho wires are generally white or yellow) should be passed through; the other two should just be snipped.
This will work, provided the aggregate load of the three fans is not too much for the motherboard. It might be, particularly since the system will probably run its fans at full power for a moment at startup, and fans draw maximum current when spinning up from rest.
A lot of LED-lit case fans only draw a couple of watts (if the fan only has a current spec on its sticker, multiply current in amps by 12 to get the power rating in watts), but the P4 fan will probably draw about 2.9 watts on startup. Your motherboard manual may tell you the maximum power rating of your fan headers; it's not likely to be much more than four watts per header.
To reduce the current draw, you could use non-lit fans with similar power, which are likely to draw almost a watt less. Glowy fans will be dim when running below full speed anyway, so you could use some separate decorative lights instead. You'd still be pushing it a bit if you want three fans running from one header, though.
Anyway, ignoring power supply problems, the most elegant way to do this would be with a three-way adapter with one plug and three sockets, which anybody handy with a soldering iron could knock together for you in 15 minutes, given the parts. You could also hardwire the setup, by just hacking the plugs off two of the fans and splicing wires.
And yes, there is another way. There are lots of fan speed control devices that have thermostat functions and one or more thermal probes. The good old Macpower DigitalDoc5 may still be the most popular of them, but there are plenty of other options.
