Sunday, December 21, 2008

the three-card game

already on the 2-card machine, I played with the os installation. initially, I installed a 32-bit RHEL 5.2 from media, only to change my mind and go for the 64-bit fedora10, which should give me a slight performance edge.

I had a nasty day or two without the X windows/desktop, since the nvidia driver version 180.06 and then 180.16 did NOT install ok. whoever wrote that script seems not to have known a magic spell I finally found on nvidia forum, you know, something like:
"/usr/bin/nvidia-xconfig -a". a spell without which your computer only outputs 24 lines of text ;-). half a day, and a bunch of rpm's later I started feeling at home in my tcsh and gnome desktop. I installed the newest sdk for cuda without incident.

then the real fun began. the physical re-installation of the water-cooled cards.
my first leak... :-( well, all those of you who used the extremely short barbs in the BFG gtx280 H2OC kit, meant for SLI installation, know what I mean. the supplied short pieces of clear lastic vinyl tubing don't tightly fit around the barbs, the white plastic clamps aren't really working and, besides, the short barbs are a bit too wide and catch on the aluminum card backplate painted in black, when you try to mount them on the card. all those mechanical/hydraulic issues
can be solved by abandoning those too-short and too-wide barb fittings and using the 3/8 inch fittings, which are smoother and better quality anyway. just one thing: you have to shorten them so that the cards are close together. I put the cards in, measured the distance and cut off pieces of four 3/8" barbs with a carbon (diamond?) disk attached to an electric drill.
I smoothed the edges so they won't cut the hoses and everything started looking good again (although I'm missing the home depot's garden hose a lot! :-)

the LQ1000 case is very compact, like all mid-towers. for instance, I musty warn those of you who would like to use EVGA water-cooled 280s that this box DOES NOT WORK with them. they're too high (from PCIe bracket on mobo to the top of the card). you have to use BFG gtx280 H2OC cards. I was just lucky to have gotten them in my first iteration. they almost touch the big fan casing, so you have to route the cooling hoses over the low sectors of the cards. there is enough tubing in the Zalman kit for several waterblocks.

those hoses will likely touch the 24cm fan casing
which is ok. the small door covering the disks will touch their sata cabling. it's all barely doable. if you install the lowest/furthest x16 card, you'll always worry a lot about the sharply bent hose coming down toward the bottom plate of the case. but it will all work! I bent and even clamped the hose in a working system with my fingers and the flow rate diminished noticeably only when I used so much force that I thought I'll stop the flow completely. but it kept going and Zalman's flow rate alarm wasn't even triggered.

in this picture you can see that I removed the white plastic clamps between the graphics cards (cf. previous pix), and installed the home-depot clamps on the shortened 3/8" barbs. no leaks now.

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