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A7V333 problems and power supplies
Ordered three A7V333 (rev. 1.02) boards back in December. (I am running
a Athlon 1700+ (0.13um) CPU in these boards.) Didn't have time to set one of them up until recently, and the other was only used a little. The one I setup in December had to have the power supply replaced in Feb. The 3.3V portion of the supply (300W) was putting out 3.9V. I lost a SCSI controller. Replaced the supply and all worked well until recently. Then the power supply started to make high pitched noises. Not the fan, but very high freq. like a fly-back inductor in the switching power supply that had a large switching current flowing through it causing magnetostriction of the magnetic core. Then.... I built another machine using one of my other boards and new CPU (same speed and also 0.13um). The box for this machine is an Antec with a 350W supply. It ran for a little less than a day and then started the make the same (more or less) high pitched sound. Now that machine reboots and gives trouble. My conclusion is that ASUS screwed up the on-board buck converter (the DC-DC converter used to step the 3.3V from the power supply down to the CPU voltage ~ 1.5V to 1.8V depending on CPU) and that is producing large ripple currents in the fly-back inductor in the 3.3V output, which is probably causing the output filter capacitors of the 3.3V section to fail since they are probably seeing large ripple current as well. The interesting part is that we have a machine in the lab that I built using a rev.1.02 A7V333, but it is using a 1900+ Athlon that was fabricated in a 0.18um process. This machine has given no trouble. It could be that the on-board buck converter produces large ripple currents when stepping down to the lower voltage that is used by the 0.13um CPU. I wouldn't draw such a conclusion, except that I have encountered it twice with 0.13um CPUs, but when a 0.18um CPU was used I have had no problems. I have ordered a 0.18um CPU so that I can experiment at home (the lab machine is not mine to experiment with) and I have a new and unused 350W supply to experiment with too. Has anyone else had similar woes? Please reply to the newsgroup and my email address. Thanks in advance. John Wilson Ph.D. Electrical Engineering Visiting Research Scientist North Carolina State University Electrical and Computer Engineering Deptartment |
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In article , John Wilson
wrote: Ordered three A7V333 (rev. 1.02) boards back in December. (I am running a Athlon 1700+ (0.13um) CPU in these boards.) Didn't have time to set one of them up until recently, and the other was only used a little. The one I setup in December had to have the power supply replaced in Feb. The 3.3V portion of the supply (300W) was putting out 3.9V. I lost a SCSI controller. Replaced the supply and all worked well until recently. Then the power supply started to make high pitched noises. Not the fan, but very high freq. like a fly-back inductor in the switching power supply that had a large switching current flowing through it causing magnetostriction of the magnetic core. Then.... I built another machine using one of my other boards and new CPU (same speed and also 0.13um). The box for this machine is an Antec with a 350W supply. It ran for a little less than a day and then started the make the same (more or less) high pitched sound. Now that machine reboots and gives trouble. My conclusion is that ASUS screwed up the on-board buck converter (the DC-DC converter used to step the 3.3V from the power supply down to the CPU voltage ~ 1.5V to 1.8V depending on CPU) and that is producing large ripple currents in the fly-back inductor in the 3.3V output, which is probably causing the output filter capacitors of the 3.3V section to fail since they are probably seeing large ripple current as well. The interesting part is that we have a machine in the lab that I built using a rev.1.02 A7V333, but it is using a 1900+ Athlon that was fabricated in a 0.18um process. This machine has given no trouble. It could be that the on-board buck converter produces large ripple currents when stepping down to the lower voltage that is used by the 0.13um CPU. I wouldn't draw such a conclusion, except that I have encountered it twice with 0.13um CPUs, but when a 0.18um CPU was used I have had no problems. I have ordered a 0.18um CPU so that I can experiment at home (the lab machine is not mine to experiment with) and I have a new and unused 350W supply to experiment with too. Has anyone else had similar woes? Please reply to the newsgroup and my email address. Thanks in advance. John Wilson Ph.D. Electrical Engineering Visiting Research Scientist North Carolina State University Electrical and Computer Engineering Deptartment There is a table of processors he http://www.qdi.nl/support/CPUQDISocketA.htm Have you set the Vcore voltage correctly for the processors you are using ? Has anything failed completely ? As in a burst capacitor or leaking brown fluid onto the board ? Abit boards like to fail like that, whereas on Asus boards, we get the occasional report of a failed MOSFET (burned and cracked). Usually when Asus screws up a Vcore design, the result is frequent processor crashes due to insufficient current or wobbly output voltage. I think with the A7V333 it is easy to apply too much Vcore. There is an overvoltage jumper, that bumps Vcore 0.3 above nominal. You should be able to use the Power Monitor BIOS page, to read the voltage, or get your trusty voltmeter, to make sure it isn't overvoltage. DDR DIMM voltage jumpers and mention of the overvoltage jumper: http://www.spodesabode.com/content/article/a7v333/print Overvoltage is mentioned here also: http://groups.google.com/groups?hl=e...news.dfncis.de Lostcircuits says it uses an Onsemi NCP5322A for Vcore (because I cannot read the part number on the chip in the picture of the board in the PDF user manual): http://www.lostcircuits.com/motherbo...a7v333/3.shtml Onsemi says the NCP5322A regulates 12V down to 1.6V at up to 45Amps (with the Onsemi reference circuit, presumably). Could the sound you are hearing actually be coming from the computer PS as it supplies the +12V ? http://www.onsemi.com/pub/Collateral/NCP5322A-D.PDF Now you can check the Asus designer's calculations :-) Paul |
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Paul wrote:
Lostcircuits says it uses an Onsemi NCP5322A for Vcore (because I cannot read the part number on the chip in the picture of the board in the PDF user manual): http://www.lostcircuits.com/motherbo...a7v333/3.shtml Both the A7V333 1.01 & the 1.04 i've looked at have location U8 occupied by an Onsemi NCP5322A. -- Please followup in newsgroup. E-mail address is invalid due to spam-control. |
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