Dan's Data letters #114
Publication date: 2 July 2004.Last modified 03-Dec-2011.
Cheap goop
I enjoyed reading your piece on thermal grease. I'm not trying to conduct heat away from CPUs - I'm trying to use Peltier modules to cool an overzealous laser that likes to heat itself to oblivion. What I came across, quite by accident, was a product from my garage called "anti-seize compound". It is used to keep threads from getting stuck on bolts and nuts, etc. It has a fair amount of fine copper powder in it, it's about the right consistency, and it's cheap; I bought half a pound at the auto parts store for about $US12. I did see some "copper thermal grease" once, but it was very expensive.
Do you see any reason why this stuff would cause any problems for me, or maybe even in a processor application?
Matt
Answer:
Yes, copper-based anti-seize compound can work well as thermal grease. There's also nickel-based anti-seize, and various
other formulations. The copper-based stuff does indeed have good thermal conductivity, and usually also has superb
heat resistance - these compounds are made to prevent seizing in things like engine bolts that get far hotter than
any CPU, so you shouldn't have any problems with the compound baking into a powder in a computer application.
However, many anti-seize compounds are highly electrically, as well as thermally, conductive. This is obviously a problem if some compound wanders onto processor pins, motherboard traces or top-of-chip contacts like the ones on Socket A CPUs. It's safe to over-apply ordinary thermal grease; it's not safe to over-apply electrically conductive compound.
Headphone hunting
I read your quite informative evaluation of the Sennheiser HD 212 and 270. I was tempted to get the 212, but at the end you had some caveats about the comfort level. So I was just wondering if you thought there was anything out there that was about as good overall as the 212, but that was even much more comfortable? Roughly the same price would be preferable, although I would not quibble about paying somewhat more for something a little better.
Leone
Answer:
If you want a more comfortable headphone than the HD 212 with the same high isolation (noise blocking), then you're
after a circumaural (big, around-the-ears) sealed-back unit. Regrettably, I have no more of those on my quite large
headphones-to-review pile, but I can still suggest a few options.
Beyer's DT 231 might suit you, but I haven't seen them, and their small earpads make me think they might not be as circumaural as you'd like. Here in Australia, Aus PC Market sell the DT 231 for only $AU108.90 delivered, so the price is right; Aussies who'd like to buy a pair can click here to order.
If you don't mind an open-back headphone (more outside noise gets in, more inside noise gets out), then Sennheiser's HD 555 (which I do have on my to-review pile) is a standout, but it's much more expensive than the 212. The 555 still doesn't cost a fortune, though; $AU231 delivered here in Australia. Australians who'd like a pair of 555s can order them from Aus PC, as well - click here.
The Sennheiser HD 280 Pro is a cheaper, sealed, comfortable option. Well, cheaper for people who live in the USA, anyway; for some reason, these $US99-ex-delivery 'phones sell for a hefty $294.80 delivered here. Aussies who'd like to buy a pair anyway can do so here, but I can't recommend them at this price.
Funky Flash
Do you think those "Ultra speed" CompactFlash memory cards are worth the extra 30 bucks? You know, the ones that claim 44X Read and 22X Write (compared to what, I'm wondering...). This here URL is a good example (scroll down).
Yang
Answer:
Fancy expensive allegedly-faster memory cards aren't worth paying for, unless you plan to be writing a lot of data
to the card very fast. If you're doing normal shooting in JPEG mode with a modern digital camera that's got enough
internal buffer space for at least a few pictures (as everything decent does, these days; the
PowerShot S410 you linked
to has a six shot buffer) then it's unlikely that you'll often, or ever, find yourself waiting for a write operation
to finish. Even if the card's achingly slow, you can always shoot as many pictures as will fit in the buffer without
having to wait; only if the buffer's out of room will you see the real card speed.
Read speed doesn't matter a whole lot, either. Even a slow card in a USB 2.0 or FireWire card reader should dump data to a PC quite fast enough for anybody, and if all you've got is a USB 1.1 connection, that'll be slower than any modern card's read speed anyway.
If you're shooting like crazy or using RAW mode, though, write speed can become important. The device that's doing the writing can make a big difference to the actual throughput, though; consumer digital cameras, in particular, generally have pretty low write speed limits, so it doesn't matter much how fast the card is, past that limit. There can still be advantages if the camera's writing data in bursts (average speed one megabyte per second, but composed of alternating half-seconds of no writing and of 2Mb/s writing...), but such weirdness is not very common these days.
Also, just because a memory card has "Ultra Super Mega Dance Dance Hyper Bass Alpha EX Fisherman 2 Rancher Rally" written on it doesn't, of course, mean it's really especially fast. SanDisk, for instance, used to be famous for making expensive "Ultra" cards that were actually rather slower than various cheap odd-brand eBay cards.
Unfortunately, I can't find any performance data for current Dane-Elec cards, like the ones being sold at the store you linked to. Rob Galbraith's CompactFlash Performance Database is generally excellent and up-to-date, but it includes no Dane-Elec products. The DPReview comparison was great when it was new, but it hasn't been updated for some time, and includes only one old Dane-Elec card.
Anyway, if the "X" numbers in the spec mean anything, they should mean multiples of 150 kilobytes per second.
Personally, my mantra for memory card purchasing is "eBay, eBay, eBay". As I said, speed can matter for real high-throughput photographers, but brand name 1Gb CF cards are listing on eBay at the moment for around $US165, ex delivery. That's not a lot more than half the price of one of those Dane-Elecs at the store you pointed to.
I'm willing to bet you'll notice the extra money in your pocket a lot more than you'll notice the (possibly nonexistent) extra speed of the fancy card!
Great Moments In Hardware Reviewing
Surfing the .net I came across this review. Seemingly yet another product to increase memory performance and make you 3733t amongst your computing brethren. What do you think?
Personally I'm actually worried that it might cause memory problems - surely all the rushing air could dislodge a byte or two.
Richard
Answer:
Increase memory performance? Well, maybe, but that review'll leave you in the dark - the author
cheerfully admitted that seeing whether the extra RAM
cooling had any effect on the overclockability of the RAM "wasn't in the scope of my review".
Hey, why didn't I think of that? I could save a lot of time reviewing stuff if I put up pages that said nothing but "Hello world!" and explained to anybody who asked about the lack of meaningful content that it "wasn't in the scope of my review"!
That reviewer also, somehow, compared temperature readings between a Thermaltake RAM cooler with a fan and heat spreader plates, and the Super Talent cooler with light-up fans but no heat spreaders, without specifying where or how the temperature was measured. I've ranted about this sort of thing before.
As I've mentioned before, including in the above-linked rant, RAM cooling gadgets are just computer jewellery. They may let you run the RAM marginally faster, but nobody has ever been able to achieve a performance difference that's anywhere near noticeable. A few extra megahertz of RAM bus speed, even if extra cooling does let you consistently achieve it, doesn't mean beans.
I can only conclude that reviewers who bother to do temperature measurements (however questionable...) but then don't bother to see whether there's a resultant performance difference are, presumably, just sucking up to whoever sent them the review gear.
After I put this page up, PimpRig head banana Gary Mullins (who didn't write the review) and I had a bit of an e-mail chat, and he filled me in about the temperature testing protocol. Apparently the RAM chip temperature was tested with a probe on the chip, which stayed in the same place when the RAM cooler with heat spreaders was installed on the module. This is, as I've mentioned before, not a great idea, since the probe interrupts the thermal junction between the chip and the heat sink; one side of the probe will be heated by a marginally cooled RAM chip, and the other side will be cooled by a marginally warmed heat spreader. But I suppose it's the best of a bad lot.
The reviewer apparently stuck another thermal probe on the outside of the heat spreader, though, and reported that its reading was only a fraction of a degree different from the one stuck on the chip. What this says is that he wasn't getting useful numbers, because the cooling fan was blowing right on the probe, there; if it didn't read considerably cooler than the probe that was sandwiched between the RAM chip and the heat spreader, then either the chip was outputting very little heat, or something else was completely broken. My opinion of the quality of the review has, therefore, not risen.
Gary also said the review would be updated with this extra information, but it's been almost a week now and it doesn't seem to have happened.
And, ye gods, here's another review of the same product, with much the same problems. Yes, pointing a fan at your RAM will make it cooler. Duh. The question is whether such cooling will give you a significant, or even measurable, improvement in speed or reliability. This reviewer, like the last one, seems to have no interest in answering that question, or mentioning that all previous products of this type have turned out to be nothing but tinsel.
Where is my flying car?
If you're into Clive Cussler you'll probably have read Atlantis Found, in which his protagonist (Dirk Pitt) and his trusty sidekick pilot an aircraft into Argentina or something... My question relates to the aircraft. It's supposed to be a Moller Skycar. Do you know if the vehicle actually exists in the stage that it is currently supposed to (so far as I know they're still mucking around with hover tests etc.), and is it actually a viable option?
If so the whole idea seems pretty exciting, if not the website seems a fairly elaborate hoax.
Liam
Answer:
Yes, the Skycar exists, and they do seem to be inching the thing towards production. They've been doing so for, literally,
decades, though; don't expect any flavour of Skycar to actually make it past the prototype stage any time soon.
Is it a practicable idea? As a general purpose transport device (for people who can afford $US500,000 vehicles, at first at least), maybe, eventually. In order for Moller to unsnarl themselves from the general aviation restrictions that currently require them to only operate the Skycar with tethers, and which will in the future rule out anybody flying it who doesn't have a proper pilot's license, though, it seems likely that someone will need to pretty much tear apart the very heart of the Federal Aviation Administration, and similar bodies in other nations.
It's not just licensing restrictions - which are obviously perfectly sensible, while the Skycar remains more or less a regular aircraft, not something flown for you by a computer. It's also stuff like mandated maintenance - Moller's groovy engines may "require little maintenance", but the FAA doesn't care. You'll still need them regularly and expensively inspected by certified mechanics at a proper airfield, until someone changes the rules. Pile up all of the restrictions and the Skycar's "advantages" over various less Jetsons-ish light aircraft start looking pretty unimpressive.
Moller seem to be under the impression that their product's success will result in considerable loosening of the restrictions... which stand in the way of their product's success. Hmm.
Maybe they'll be able to get it off the ground (literally) in countries with less entrenched aviation bureaucracies than the USA, but even then the notion of putting even a highly automated, allegedly idiot-proof aircraft in the hands of a normal car driver is lunacy. We just don't have the continent-wide, high-resolution, triple-fail-safe automatic-navigation systems that'd be utterly essential to stop people planting the things through roofs, through power lines, through hillsides - and such systems are not going to hit the market soon. The "airway network" Moller envisages is, at the moment, still a complete blue-sky dream.
Mind you, GPS sounded similarly ridiculous in 1970. Now everybody can get full military precision for a couple of hundred bucks.
No-fuss tanking
My father's 60th birthday is coming in a couple of weeks. I want to buy him a model already made. Where can I buy a Sherman tank already built?
Gil
Answer:
Why, right here!
What's that? $US3500 a bit much for you?
If you only want a little indoor rubber-track model, there are a fair few options, though actual Shermans can be hard to find unless you go really small. EBay's got a whole category for R/C tanks these days.
If it's got to be a Sherman, though, or you just want something that can conquer more than carpet, you need the tank to have proper articulated tracks, reasonable size and a bit of motor power. The rubber-track Doyusha Abrams (no, it's not a Sherman) is a price/performance winner, but still not really an outdoor toy.
For genuine all-terrain play, there's really not much out there that's cheaper than Tamiya's kits, and those you have to build (or have someone at a hobby store build for you, which may take a few weeks). Tamiya sell pre-built versions of some of their car kits (these, for instance), and there are some pre-built military kits as well, but they're not R/C. So you could be stuck.
Mind you, there is something to be said for giving someone a Tamiya kit, radio, batteries, charger, paint and any tools they don't already have. It's not as if they have to build the thing from scratch (wow!).
Probably waxes the car, too
Have you ever heard of The Frequency Center's "Fuel Disc"? I saw it on my local news, because the company is in my local area. The news lady said it improved her gas mileage and the trucker she talked to said it helped his, also. At over $US130 per disc, I feel a little skeptical, but how could the news lie to me?
Merrick
Answer:
The Frequency Center have gotta be frickin' kidding.
They make magical devices that're meant to give the usual marvellous improvements to mileage, emissions, blah blah blah, but wait, they also have gadgets that're meant to improve the insulative value of windows, and other gadgets that're meant to help you lose weight!
The reprinted press release here sums up their automotive claims quite well; vague notions about "frequencies" (they used to be called "vibrations", until The Beach Boys and others spoiled the word) that've been advanced by thousands upon thousands of scam artists of all kinds over the years. Similar claims have been made for hundreds of miracle medicines that don't work, hundreds of mystic jewels and charms that don't work, and hundreds of other miscellaneous crystal, blessed and otherwise occult devices and talismans and salves that, you guessed it, don't work.
The Frequency Center's evidence for the effectiveness of the Fuel Disc? A failed (PDF) and then a passed (PDF) smog check result for a '94 Nissan which, assuming the documents are even genuine, could just have had its rings replaced, or something. They could have put some castor oil in the fuel tank for the first test. They could have slipped the tester $US127.50 (which I'm betting is their approximate profit margin per $US130 disc). They could have done anything.
If my friend that I trust showed me these results and swore he'd just stuck a magic disc to the fuel tank to make the change then I'd be interested, and willing to try an informal test myself - but these people are selling the things, so obviously proper independent test results are needed.
The rest of their evidence? Uh... they've got some testimonials. So does every other nut on the tree. And that's about it, apart from a bit of blather about theosophy, of all things. Another multi-billion-dollar innovation, sadly kept from the eager-to-make-the-inventors-rich-beyond-their-dreams public by a bizarre and inexplicable lack of any attempts to show that it actually does the incredible and revolutionary things that it's meant to do.
(I am, by the way, strongly reminded of the EMPower Modulator.)
Regarding being lied to by the news - in further correspondence, Merrick said that the news report he saw was "genuine", at least in so far as it used a regular reporter and wasn't just a repackaged "Video News Release", also known as a video press release. It pays to bear the existence of those things in mind, though; no longer do cash-strapped local TV news outfits have to come up with their own poorly researched stories; now they can just broadcast one delivered directly to them by PR people!
Regional TV news in the USA is famous for running VNRs instead of real news. The major stations in the US and elsewhere now do it too, especially when the VNR has enough star power, but the majors don't have to do it because they're out of other content to show. Little stations need something to fill air time, and video press releases that look like a real report (maybe with a new voice-over from one of the TV channel's reporters, maybe not) cost them nothing. All kinds of crap makes it to air (and into print - newspapers reprint press releases, too) this way.
