Messages in this thread | | | Date | Wed, 23 Jul 1997 15:29:12 -0700 | From | Don Fisher <> | Subject | What kind of chip is this 200 or 233? (OFF TOPIC) |
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Hi,
Just for info. I purchased a 200 MHz MMX. I was able to overclock the bus frequency and achieve:
Bus Speed CPU Speed (from boot msg) 66 MHz => 200 MHz 75 MHz => 230 MHz 83 MHz => 250 MHz
The 200 MHz part uses a 3.0 bus multiplier. I then tried the 1.5 multiplier that works for 233 MHz part, and SURPRISE, the chip came up at 233 MHz! I then tried the 75 MHz bus speed and the chip went to 266 MHz. When I tried the 85 MHz bus speed the chip said it was still a 266 part, but couldn't read the disk to boot linux.
Bus Speed CPU Speed (from boot msg) 66 MHz => 233 MHz 75 MHz => 266 MHz 83 MHz => 266 MHz (but dosen't operate correctly)
The actual execution times for compute bound tasks is near identical even with the 6% clock increase. For 1024x1024 FFT (of a single precision image) it took 1.7 seeconds while at 266MHz it took 1.71 seconds, a 0.5% increase. So the increase in memory speed caused by the 83 MHz bus clock (up 10%) balances the the increase in CPU clock speed.
For now I have deceded to be conservative, not pick on the memory or PCI devices and run at 75MHz. Anybody know how to get the 85MHx bus clock to work?
don -- ******************************************************************* * Don Fisher dfisher@as.arizona.edu * * MMT Observatory VOICE: (520)621-7647 * * University of Arizona FAX: (520)670-5740 * * Tucson, AZ 85721 * *******************************************************************
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