Sunday, November 11, 2007

Heat, Speed, & Sound


Mr. Tobias Schonherr pointed out an error in my assembly of this new computer. Thank you Mr. Schonherr! I had misinterpreted the Intel manual on the DP35DP motherboard, and unwittingly installed the two memory modules in single-channel mode rather than dual-channel mode.

As I understand it, dual-channel mode enables the CPUs to make two requests on memory at one time, increasing overall memory throughput. See below. First the memory modules before and after, then the resulting Windows Experience Index before and after. The computer recognized 4 Gb of memory in each case, but you will notice that the memory sub-index jumped from 5.6 to 5.9, now as high as any other element of the system and higher than the dual-processor CPU.
Before After
Memory as originally installed Memory correctly installed
Original Windows Experience Index New Windows Experience Index


Modern computers contain a host of self-monitoring devices, temperature monitors in particular. I installed the Intel Desktop Utilities, which takes advantage of those devices to provide readouts and to raise an alarm if some device goes outside its limit.

A few days back I returned to my computer to find an alarm on the screen. The CPU had exceeded its temperature limit of 68 degrees C for several minutes, going as high as 69 C (156 F). I downloaded a system-exerciser program called HeavyLoad and ran the CPU test, which is a repetitive graphics application, and the CPU temperature jumped right up to 70 C, CPU fan becoming very audible. Oops - problem.

I wondered if the thermal transfer between the CPU and its heatsink was OK. I had removed the heatsink once to re-check that the CPU was correctly loaded in its socket, thus disturbing the termal transfer compound. Also I had never felt good about the seating of the clips that hold the heatsink to the motherboard.

So I removed the heatsink once again, removed the old thermal transfer compound, and applied Arctic Silver compound in its place, evening it out with a credit card. Replacing the heatsink atop the CPU cover, I tried very carefully this time to apply equal pressure on all of the mounting clips, hearing a satisfying little click at each corner, an assurance that the heatsink is held down squarely. I also disconnected the internal case fan from motherboard control and connected it to full voltage so that it will always run full speed. It's noiseless anyway.

Good results! The following measurements were made with HeavyLoad executing its graphic application (about 60% CPU utilization), and the hole pattern in the back of the case blocked, thus forcing air to come all the way through from the front). In each case, temperatures were allowed to settle for at least a quarter of an hour. The CPU fan is automatically controlled from the motherboard:

  C C C C C Fan
Max allowed 68 85 119 109   RPM
Exhaust fan LOW (silent) 60 48 62 66 53 1467
Exhaust fan MED (audible) 60 49 62 66 50 1345
Exhaust fan HI (whoosh) 59 47 62 66 50 1348
Fan LOW, no HeavyLoad 40 41 63 66 53 927

I wish it were cooler still, but the CPU is now well within specifications. Further, the speed of the rear exhaust fan doesn't seem to make much difference in the temperatures, though it makes a lot of difference in noise. So I'm leaving the fan on low until there is a problem.


I admit that my hearing isn't what it once was, but this system is so quiet that I can't always be sure I'm hearing it. A very low rumble from the disk drives is about all there is, and only when they are busy. But when the forced-air-furnace comes on I just can't hear it at all. I LOVE that! Now about that furnace ...

Sunday, November 4, 2007

The Computer Is Built!

And I'm pleased with it.


Windows Experience Index screen in Vista, click to enlargeThe overall Windows Experience Index is 5.4, which I believe is pretty good. The limiting subscore (5.4) is the disks, actually, and they are very high-speed SATA II 7200-RPM drives, though you can get 10,000 RPM drives which should be faster yet. The highest subscore is the Windows Aero graphics, 5.9. Everything else falls between, so the system is reasonably well balanced.


When there is nothing else going on in the room, TV and the old computer turned off, sitting at my desk, I can hear a faint, low-pitched roar similar to the sound you hear by holding a large seashell up to your ear, but certainly not that loud. It has a resonance to it, despite my efforts to dampen sounds inside the box. I think that the rear fan is the origin of most of the noise. It's not objectionable, because it's faint, but I will probably try to do more to limit the sound, such as: This is the computer (black), in service, next to the older and larger Gateway 600 (grey) that it will eventually replace.  Click to enlarge
  • Add more sound-deadening material inside the box; there is room on the side cover for more;
  • Play with fan speeds. The computer reports its own temperatures at several places including the CPU, graphics card, and motherboard, and those are quite comfortably within spec right now, so I could choose a lower speed for the rear fan;
  • Cover the strange hole pattern on the back of the case, for which there seems no purpose; and
  • Replace or rewire the rear fan. The motherboard came with a fan-control connection for that fan, but oddly, that fan did not come with a connector for the fan control. It may be easier for me to order a fan with the right connector rather than a conversion cable.
Bottom Line:

It's a good computer. Luckily there were no DOA (dead-on-arrival) parts, and it came right up and ran. The only problems were software ones, after Vista was installed and not to be discussed here (though I may yet post a rant about Vista. It is SO awkward and obtuse). I think that once a person has the proper parts on hand, one could put a computer like this together in an hour or two, including the initial Vista installation.

Below is a pictorial of the build process, in reverse order. Click on the Materials List on the side panel to see what went into the computer.

Initial RAID Screen in Intel Bios
After powering up the disks, this screen in the BIOS allowed the association of drives A and B as a single fault-tolerant 320 Gb RAID disk before anything was ever written to the disks.

Screen shows that no bootable devices are connected.  More importantly, it shows that the computer WORKS!
When first powering up the system, I had disconnected all of the disk drives and some other stuff to see if the CPU and motherboard would POST (power-on self test). THEY DID! This screen proves that a lot of stuff was working:
  • Power supply;
  • Motherboard;
  • CPU;
  • Graphics card, at least sufficient to display to the generic screen; and
  • USB ports and keyboard-handling firmware on the motherboard;
  • Fans (I could see them turn).
Ready to run
The box is fully wired and ready to test.

Motherboard and most other parts are in place
The motherboard is installed and screwed in place.

Hard disks are installed
The three 320 Gb hard drives are in place and wired up. Two drives are for the fault-tolerant RAID disk, and a third will be used as a backup.

One 320 Gb drive
It's still hard for me to reconcile this palm-sized, silent, extremely fast 320 Gb drive with the washing-machine-sized sub-Gb drives I cut my computer teeth on years ago. And in just a few years, even these will be replaced with much faster flash drives having no moving parts at all.

Sound deadening material applied
Sound-deadening material stuck to the back side of the hard-drive cage. A similar piece is attached to the side door covering the drives on this side, and on the bottom and top of the cage. I attached this material on all interior surfaces wherever it could be attached without getting in the way or interfering with the passage of cooling air.

Sound-deadening felt
Sound-deadeing felt. Found in the local Menards hardware store, not for the purpose of deadening sound, but I think it should work. I liked the black better, but the store didn't have much so I bought some of both.

Front fan is installed
Front fan installed inside of the hard drive cage, to pull air across the drives and blow it toward the graphics card and CPU. See earlier posts for other views of the entire case.