ong@d.cs.okstate.edu (ONG ENG TENG) (01/23/91)
Well, a certain Mr. M (thank you) from Finland told me that his friend successfully sped his 16MHz 286 up to 25MHz with a small fan. Hhhhmmm... beside the CPU that is warm (at 20MHz), the other chips seems pretty cool. The C&T chips, the other decrete components, DRAM's, seems OK. The only thing that is hotter than the CPU is the *big* serial chip on my multi-serial card (that's the one chip you have to add for an extra serial port, I got 4 on mine for 4 serial ports). Anybody wanna stop me (yeah, like you would stop the astronunts (sp?) from going to Mars!)? Also, I was asked where to get the oscillator? It's from Digi-Key, 800-344-4539. Part# for 40MHz (20MHz operation) is X120 or CTX120. Part# for 35MHz (17.5MHz operation, if you worry about the heat) is CTX134. If you are braver, and wanna to go for higher speed, ask the Digi-Key operator for higher speed X series or CTX series oscillator, and be sure to let us know! (no, we wouldn't give you a prize). Also, I got a 35MHz and another 40MHz oscillator extra. Anyone wants to come to Stillwater, Oklahoma and get one for $4? Could anyone define hot on a chip (that requires heatsink)? I know when a chip is too hot (i.e. ready to burn out), but mine is kind of slightly below that. I can put my finger on it for minutes and my finger would not burn, but it is quite uncomfortable. Thanks in advance E. Teng Ong (ong@d.cs.okstate.edu) 800-344-4539
phil@brahms.amd.com (Phil Ngai) (01/24/91)
In article <1991Jan22.160249.5110@d.cs.okstate.edu> ong@d.cs.okstate.edu (ONG ENG TENG) writes: |Well, a certain Mr. M (thank you) from Finland told me that his friend |successfully sped his 16MHz 286 up to 25MHz with a small fan. |Hhhhmmm... beside the CPU that is warm (at 20MHz), the other chips |seems pretty cool. The C&T chips, the other decrete components, DRAM's, |seems OK. The only thing that is hotter than the CPU is the *big* serial |chip on my multi-serial card (that's the one chip you have to add for |an extra serial port, I got 4 on mine for 4 serial ports). Anybody |wanna stop me (yeah, like you would stop the astronunts (sp?) from going |to Mars!)? I don't want to stop you, but I think what you are doing is not wise. However, it is your equipment to do with as you wish. It is your data at risk. |Could anyone define hot on a chip (that requires heatsink)? I know |when a chip is too hot (i.e. ready to burn out), but mine is kind of |slightly below that. I can put my finger on it for minutes and my |finger would not burn, but it is quite uncomfortable. Most chips are rated to operate properly at a temperature that you probably could not stand for more than a few seconds. (max ambient temperature of 70 degrees C. the military stuff can go to 125 degrees C, or hotter than boiling water.) The temperature of a chip is not a sure-fire indication that it is not being run beyond specification. Nor does running a single chip within specs mean that the board will function as designed. Your obession with temperature and clock rates is misdirected. A chip is not like a mechanical device which overheats when it is overloaded. The real dependences are as follows: 1) Most chips' maximum speed of operation decreases with increasing temperature. 2) Most chips' power dissipation is a roughly linear function of clock speed. 3) Most chips' maximum speed of operation increases with decreasing temperature. (this is the same as 1 but I wanted to be explicit about this) 4) Most chips' are tested to a small margin beyond their specifications to allow for the lack of perfection in the equipment used to test them. We want to be sure that "even if our speedometer reads 5 MPH low, we are still within the speed limits". And, they are tested at the maximum temperature specified. So at room temperature, there will be some margin. But how much? Unless you are an engineer and fully analyze the circuit, you don't really know if it will still be reliable after your changes. As far as I'm concerned, it is foolish to risk your valuable data to this kind of folly. Although I work for a company which makes semiconductors, I don't speak for them. I don't think they would disagree with me, however. There are companies that make chip coolers (Velux). However, they don't intend that you just crank up the clock rate. The entire design needs to be analyzed and any timing problems corrected. Otherwise you are gambling with your data. -- When someone drinks and drives and hurts someone, the abuser is blamed. When someone drinks and handles a gun and hurts someone, the media calls for a gun ban.
als@bohra.cpg.oz (Anthony Shipman) (01/24/91)
In article <1991Jan22.160249.5110@d.cs.okstate.edu>, ong@d.cs.okstate.edu (ONG ENG TENG) writes: > Well, a certain Mr. M (thank you) from Finland told me that his friend > successfully sped his 16MHz 286 up to 25MHz with a small fan. > Hhhhmmm... beside the CPU that is warm (at 20MHz), the other chips > seems pretty cool. The C&T chips, the other decrete components, DRAM's, > seems OK. The only thing that is hotter than the CPU is the *big* serial > chip on my multi-serial card (that's the one chip you have to add for > an extra serial port, I got 4 on mine for 4 serial ports). Anybody > wanna stop me (yeah, like you would stop the astronunts (sp?) from going > to Mars!)? A general rule of thumb for silicon technology is that each 10 degree Celsius rise in chip temperature halves the lifetime of the chip. (So a 20 degree rise reduces it by a factor of 4 etc.) Also the chip temperature can be quite a bit higher than the package surface temperature with a safe maximum of around 125 deg C for quality parts. Aside from those the reliability of the circuitry may be reduced i.e. more soft errors or greater chance of mysterious crashes. -- Anthony Shipman ACSnet: als@bohra.cpg.oz.au Computer Power Group 19 Cato St., East Hawthorn, Melbourne, Australia D