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Hello, folks, |
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|
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For those of you who remember my threads from before regarding X halts, |
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SMP kernel halts, etc, etc... I think I was able to track down the issue, |
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with Riyad's kind guidance :) |
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|
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It turned out to be an issue with my power supply, I believe. |
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|
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I did, however, run a lot of tests, about which some of you might be |
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interested to know. First, I thought it could be my IDE drives or the IDE |
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controller. So, I put a good Seagate SCSI drive in my system, did a fresh |
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install of Gentoo, and tried several versions of the kernels - |
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2.4.19-gentoo-r7, 2.4.19-gentoo-r10, 2.4.20-vanilla, and |
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2.5.52-development. The crash was reproducible with either kernel and the |
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development kernel was no more unstable than the others. After |
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reproducing the crashes without any devices hooked up to IDE or Floppy |
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controllers, it was clear that it wasn't a controller or the drive |
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problem. I also tested with each kernel whether it was a hyperthreading |
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issue or not, and it wasn't. This may seem like obvious junk, but it does |
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take quite a bit of time to test all of these configs out. By the end of |
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the week (yes, a week), it was clear that it's either the power supply or |
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the board itself. |
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|
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There was an idea from others that my nVidia GeForce3 card could be |
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conflicting with the Tyan board, or drawing too much power or something, |
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but I proved that untrue by reproducing all the crashes in the text-only |
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mode. |
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|
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I use a Tyan Thunder i860 S2603 dual board with 2.2-gig Intel Xeons, and |
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this board has received very good reviews in all the reviews I've seen. |
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Actually, Tyan makes excellent boards... Period. Power supply was an |
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easier and less expensive (and a more probable) thing to try :) I had a |
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460-W Zippy Emacs (Taiwanese) supply in my box, which came from the guys |
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who sold me this machine. I decided to go for the best this time and |
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purchase Antec's True550 EPS12V power supply for dual Xeon boards. My |
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Tyan board requires a 24-pin main Molex power connector and an auxiliary |
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8-pin Molex power connector. An EPS supply accomodates the number of |
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pins, but as I found out when I hooked it up, the pins are all in the |
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wrong places!! So I plug it in, turn it on... Silence. A few mins |
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of Googling yield a big DUH as to why I didn't do the search before. |
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S2603 is a non-EPS board, which means it needs an EPS-to-nonEPS converter, |
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which is sold my Enhance Electronics (out of California, |
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www.enhanceusa.com). Surely I could make one myself (I had schematics in |
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front of me), but most people who could have the tools (electrical |
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engineering department) were gone for Christmas! I didn't have any |
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Molex connectors or crimpers on hand, but Enhance Electronics gave a |
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nice schematic of the adapter, if anyone is curious. So I had to buy this |
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converter and now things look (and sound) pretty sweet. The system is up |
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and running. The problem seems to be gone, unless it was something else |
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(i.e. the board). |
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|
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One more note for some of you who have run into such mysterious crashes |
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before. There's not a great deal of material about this on the net. |
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Apparently, these are mostly caused by low voltages or noise on the +5VSB |
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line from the power supply to the motherboard, which is a "standby" |
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voltage line. This certainly explains why my system wouldn't awaken from |
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sleeping in Windoze. :) This also explains why the system would halt |
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after performing a string of strenuous operations. I wonder why it halted |
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in the middle of strenuous operations, if it's really a VSB problem. |
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Maybe the power supply wasn't too good and the voltages would droop at |
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high load on other channels as well. I didn't check it with a meter. |
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No time. |
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|
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It's never good to go cheap on power (or ram, or anything for that |
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matter). If one really doesn't want to replace a power supply, they can |
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put a capacitor between Common and +5VSB lines, which stabilizes the board |
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by eliminating such voltage droops and noise on the VSB line. The |
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capacitor I've seen used on the web was an electrolyte 6.3V rated 1000 |
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micro-farad capacitor (although I wouldn't bank on it, it was hard to |
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tell from the photo what Farad units those were, but numbers were pretty |
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clear :)). The power cable extension with such a capacitor built-in is |
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sold by www.highpowersupply.com (JDResearch). They only sell this for the |
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usual 20-pin power connectors, not the 24-pin ones. I ordered it just to |
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see for myself which exactly capacitor is on it ;) THe principle is the |
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same for 24-pin lines, and one could trivially make this if they had a |
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soldering iron on hand and the right capacitor. |
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|
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So, here are the pearls... Enjoy! :) This was a result of lots of |
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searches. So - if you get mysterious crashes and system halts that point |
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to other things than I/O devices, replace the power supply or try putting |
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a capacitor between +5VSB and Common to stabilize the board. |
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|
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Gentoo rocks. :) Jeez, the installs are soo damn fast now that I have |
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half-the-clue as to what I'm doing in Gentoo :) |
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|
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A brief note on the 2.5 dev kernel. It's real cool!! It compiles in a |
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flash, it loads in a flash, and I haven't run into any instabilities with |
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it yet!! It's absolutely blazing compared to 2.4.20 vanilla (or |
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2.4.19-gentoo, sorry :)) The only thing is, the nVidia kernel modules |
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don't compile with this kernel. The modules are now called *.ko rather |
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than *.o :) |
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|
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Alright, this is all for now. Sorry for making this so long, but there's |
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so much to share. You all guru's have probably been thru most of this |
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already, so forgive me for insulting your intelligence with this, but it's |
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pretty exciting stuff to a novice like me! |
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|
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All the best to everyone for the Holiday Season! |
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Denis |
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P.S. Riyad - Many thanks!! You rock!! |
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|
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_________ |
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|
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Graduate Student |
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Chemical Engineering |
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Princeton University |
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Princeton, NJ 08544-5263 |
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