swanson@UXE.CSO.UIUC.EDU (Amy Swanson) (10/20/89)
We have a lab of 20 IRIS 4D/20s and will be moving the CPUs out of the room. The CPUs are to be "rack mounted", and I'd like to know if anyone has done/thought of this. I would like to know if anyone has had any experience with simply moving a CPU about 75'-100' from the monitor and the wonderful things I can expect to happen from this; as well as any opinions on a rack design for the CPUs. Thanks, Amy Swanson SGI/Alliant Systems Administrator NCSA - National Center for Supercomputing Applications University of Illinois at Champaign-Urbana email: amys@ncsa.uiuc.edu
mike@BRL.MIL (Mike Muuss) (10/21/89)
SGI has told us that 75' of cable is the "design limit" for good quality on the Iris machines. Personally, I can't stand the noise of the CPUs, so I *always* remote my Iris. Usually I use the 75 foot cables that we pay SGI to provide us. In one circumstance, I had to remote my display about 175 cable feet. The image was still surprisingly good at that distance, although the fact that the cable was run over the fluorescent light fixtures for about 80 feet of that resulted in some 60 Hz noise being picked up, but it was tolerable. If you have a processor that will be running a (video) film recorder, or driving an RGB-to-NTSC converter for video tape, do NOT remote that display. Keep your video cable lengths as short as possible, and use the best coax you can afford. (There is a special kind of Belden coax to use for this purpose, I don't recall the number off hand). The astute eye (and ear, for sound) can see (hear) almost any kind of regular noise in the signal. (If you think I sound fanatical about video quality, you should hear the lengths I take to preserve sound quality). I have no experience rack-mounting SGI equipment. For that, you need a mechanical engineer. Best, -Mike
madd@world.std.com (jim frost) (10/23/89)
At my previous job we had a 3100 (the nice tall one with the very big fans :-) which was put in another room to make life bearable. It was a fairly long run (if 75' was SGI's max recommendation, it was pretty close to that if not over). Worked fine enough for me. Flourescent lights were along the cable run so there should have been quite a bit of interference. jim frost software tool & die madd@std.com
zombie@voodoo.UUCP (Mike York) (10/23/89)
In article <8910201651.AA15183@uxe.cso.uiuc.edu> swanson@UXE.CSO.UIUC.EDU (Amy Swanson) writes: > > > ... I would like to know if anyone has had any >experience with simply moving a CPU about 75'-100' from the monitor and the >wonderful things I can expect to happen from this;... > We have 23 4D/70's that are cabled between 135' and 189'. We haven't had any real problems with this, although some of our users claim some of the displays are somewhat "washed out". This may be due to the cable length, but is seems to be caused by differences in the individual displays. SGI told us the supported limit was 75', so we usually move a bad display to a machine with 10' cables to prove the display is bad before calling SGI to fix it. -- Mike York Boeing Computer Services, Renton, Washington (206) 234-7724 uw-beaver!ssc-vax!voodoo!zombie
ldl@uvm-gen.UUCP (Louis D. Langholtz) (10/24/89)
From article <8910201651.AA15183@uxe.cso.uiuc.edu>, by swanson@UXE.CSO.UIUC.EDU (Amy Swanson): > I would like to know if anyone has had any > experience with simply moving a CPU about 75'-100' from the monitor and the > wonderful things I can expect to happen from this. We have seperated CPUs from their keyboards and monitors by cables around 80' long with no noticable effects. However, we did use cables that have extra shielding, and are thicker (RG-59) but less expensive than sgi's cables. These CPUs are shelved on metal racks from Reliance in NJ. We have had no problems with them. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Louis D. Langholtz Systems Programmer EMBA Computer Facility USENET: ldl@uvm-gen.uucp University of Vermont CSNET: ldl@uvm.edu Phone:(802)656-2926 Burlington,VT 05405