Is there anyone powering 3 S7 with this? Which fan do you use / recommend for cooling the PSUs?
I am. My own contraption, but the same end result as j4bber's breakout board. His solution is just much more elegant. I'm using 2 Delta fans, approximately 150CFM each. Could get by with lesser fans, but I had these on hand so why not.
Sometimes, PDU's come into play. For instance, my 30 amp PDU's have two 15 amp legs. 15 amps x 220 volts = 3,300 watts. 6,600 watts maximum with both 15 amp legs combined.
I'm presently using IBM 2880 PSU's to power 2 x S7's on each PSU. 1220 watts x 2 = 2440 watts. I might use 2 x IBM 2880's and 1 x Corsair AX 860 on one 30 amp PDU to power 5 x S7's instead of using only 1 x IBM 2880 alone on each 15 amp leg of the 30 amp PDU. However, more than likely, I will end up powering only 4 x S7's with 2 x IBM 2880's for each 30 amp PDU to remain well within the 75% allowed for each circuit.
I may probably go with this new setup J4bberwock has come up with once all of my IBM's are in use [22 x total IBM 2880's]. I would have the option to power 5 x S7's comfortably on one 30 amp PDU with 2 of these new setups of J4bberwock's [One for each 15 amp leg on the 30 amp switched PDU's].
Man, I can't even imagine the noise 22 of those would make.
Why are you only getting 220V from your service? Should be 240V. Mention that when the engineer comes by, he'll send a team of linesmen to increase voltage on the transformer in the pole. They bumped mine up after I complained about having only 227V with my heavy load.
It really depends on the meter you are using. Most of the meters I use have an internal resistance of 10 million ohms or higher, which gives a 240 Volt reading. If you use an old analog triplet model 310 meter with an internal resistance of 1 million ohms, you will see approximately 220 volts. The less resistance the meter has internally when measuring voltage, the less voltage you will read. The higher resistance internally inside the meter when measuring voltage, the higher voltage you will read.
Also, I'm reading 11 amps on a PDU that powers two S7's [Batch 1] with an IBM 2880W PSU. If you multiply
220 Volts x 11 amps, you get 2,420 watts. If you divide 2,420 watts by 2 S7's [Batch 1 @ 600 MHz), you get
1,210 watts. How many watts were the S7 batch 1 clocked at 600 MHz rated? Answer:
1,210 watts.The internal resistance of ANY meter [When measuring voltage] is high. However, some meters have higher resistance than others. Some meters [Especially analog meters] have "ranges" you can select when measuring voltage and the internal resistance of the meter can vary depending on the range you have chosen. The Triplet model 310 states on the meter it is 20,000 ohms per volt internal resistance. If you put the meter in the 60 volt range, 60 x 20,000 = 1,200,000 ohms internal resistance.
If you were in the 120 volt range, the internal resistance would be 120 x 20,000 = 2,400,000 ohms internal resistance. If you were in the 300 volt range, the internal resistance of the meter would be 300 x 20,000 = 6,000,000 ohms. Which see:
The previous internal resistance when measure voltage concerned measuring DC Volts with a Triplet model 310 analog meter. When measuring AC Volts with the model 310, it's internal resistance is 15,000 ohms per volt. Which see:
If you were in the 300 volt range with a Triplet model 310 measuring what you may think is a 240 volt circuit, you would see approximately 230 to 233 volts because it has 4,500,000 ohms internal resistance in the 300 volt range (300 x 15,000 ohms per volt AC). If you used a Fluke digital meter with an internal resistance of approximately 8,000,000 ohms to measure voltage on a 240 volt AC circuit, you would see approximately 240 volts. The internal resistance of a meter when measuring AC Volts is generally a little bit lower than the internal resistance of the same meter when measuring DC Volts. However, they are both (AC and DC) still quite high.
I do not doubt you read too low of voltage at 227 volts with your meter. The power company can adjust the voltage output on most transformers. All I'm saying is the amount of voltage one reads can vary by what meter they use. Especially, if they switch from an analog to digital meter or vice versa.
If you look back at my previous statement about the 11 amps reading on my PDU, that will tell you my voltage in my home is 220 volts when you compare it to how many watts 2 x batch 1 S7's will consume when set at default of 600 MHz [1,210 watts each for a total of 2,420 watts]. I've seen a lot of 3 Phase voltages read 208 volts. Does this mean the voltage is too low? No, that 208 volts would be read with an analog meter with a lower internal resistance than a digital meter set to a higher internal resistance that reads about 215 volts.
Many people who work with electronics on an everyday basis will tell you they are careful about what meter they use when measuring voltage on a low voltage circuit verses a high voltage circuit. It can make a big difference. Especially, with low voltages.
I think you know I'm getting a power upgrade here at my house soon from 200 amps to 600 amps [or at least 500 amps]. I'm going to ask the engineer [When he arrives in the next few days] what the line voltage is on each phase coming into the neighborhood. It's very possible the line voltage is 240 volts or 480 volts and the transformer is stepping it down to 220 volts instead of 240 volts. If they in fact have 240 or 480 to start with before knocking it down to 220, I'm going to ask for a transformer that knocks it down to 240 instead of 220. It may be they have a transformer they can install to adjust the voltage output to 240 for me. Many transformers have that capability depending on where they terminate the feeder cable on the coils in the transformer.
Again, the reason I believe my voltage is actually 220 volts is because of the amp reading I'm getting on my PDU with 2 x S7's that are batch 1 and set at 600 MHz. They are supposed to burn 1,210 watts each at the wall. Two of them would be 2,420 watts at the wall. If we divide 2,420 watts by the 11 amps I'm reading on the PDU, it equals 220 Volts. I'm definitely asking them if they will increase it to 240 volts when they install a new transformer.
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