Thanks for the voice of experience. I've obviously been over-estimating them. How can one determine the power requirements for individual cards? Dick
Dick, I have personally have seen lists online of what people say are the power requirements of individual cards, but nothing official.
Thanks, Justin. I have posed this question to EVGA Tech Support and I will report back what they say. By the way, if you can point me to one of those lists that happens to cover EVGA/Nvidia cards, would like to take a look. Thanks. Dick
Sure thing. Heres one I found a day or two ago. http://www.tomshardware.com/reviews/geforce-radeon-power,2122-6.html
Thanks. The article was interesting (though not terribly kind to "cheap" PSUs that only provide 17A on the 12-volt rail ::smile:: ) and I've saved the load table. Some of the comments, however, were really unbelievable. According to some of the commenters if you only load a 500 watt PSU with 400 watts, then you are really stupid because the PSU is burning off those other 100 watts all by itself. I suppose if you unplugged everything from the PSU then it would consume the entire 500 watts by itself. Unbelievable. Thanks, again, for the reference, Justin. The load table itself looks quite reasonable as does the testing methodology. Dick
No problem. I agree. Some of the comments were quite outrageous, but the chart itself and the method behind it seem plausible.
Will do. They promise responses within 1-2 working days. Hopefully something by Friday. One of the more coherent commenters on Tom's list asked an interesting question regarding how much of the power feeding a given card is coming straight from the motherboard's PCI-E connector and how much is coming in externally from the PSU's connection to the card's 6-pin PCI-E power connector. This could be another interesting research project. Dick
I was curious about this myself in fact, but am not sure that there is a way to figure it out for certain. Despite my obvious lack of knowledge when it comes to PSUs, I have been working on and building computers for many years, and am quite competent in doing so. I guess some where along the way the fact that your PSU really is an important factor in building a solid pc eluded me. Not sure why, but perhaps it is due to me never really having enough money to build a decent gaming rig until recently. I suppose that when all you have to work with are hand me down dells and cheap old athlon boards, the difference between a 300 watt 1X 12+ volt rail at 24 amp PSU and a 700 watt 2X 12 volt rail at 70 amp per rail psu is sort of irrelevant. ( I just pulled these number out of my ass bye the way)
I khow you you feel. I'm used to working on this stuff, but I'm not used to having to guess what the various card power requirements are. I have a bad habit of believing what the manufacturers tell me and then I go and make erroneous assumptions based on those facts. I'm still learning... If I'm able to strike up any kind of conversation with the EVGA guys I'll see if I can bring that question into the mix. Dick
I had a thought, but it didnt pan out. I thought that since a pci-E slot provides 1.5 volts and 75 watts, that if I converted that into amps with this handy dandy tool I found, I could figure out how many amps were being provided by the board, and how many directly from the PSU. I was wrong. http://www.supercircuits.com/resources/tools/Volts-Watts-Amps-Converter Justin
There is a simple formula for relating watts to volts to amps: P = I * E. P = watts, I = amps and E = voltage. Multiplying volts times amps will give you watts and with simple algebra once you know any two values you can calculate the third. The problem with your theory, though, is that there are actually three voltages present on a PCI-E socket. Out of the 164 pins on a 16x socket, five of them supply 12 volts, four of them supply 3.3 volts and the rest are used to move a whole bunch of data based on a 1.5-volt protocol between the motherboard and the card. So the 75-watts provided by the PCI-E socket will be shared between the 12-volt, 3.3 volt and all of the 1.5-volt data connections. I have no idea how much 12-volt current is actually obtained from the PCI-E socket vs. from the external 12-volt power connector(s). It most likely varies from card to card with the majority of it supplied by the external connectors. I got a response from EVGA today on my query that danced around the question without answering it. The response ended with a statement to the effect of "if you don't like my response, you can contact my manager at this address.) So I reposed my question to the manager to see if I can get a better response. We shall see... Dick
