PCI express risers to use multiple GPUs on one motherboard - not detecting card?

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Ian&Steve C.

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Message 96396 - Posted: 4 Mar 2020, 4:10:48 UTC - in response to Message 96384.  

now that SETI is back. here's the leaderboards for good measure

https://setiathome.berkeley.edu/top_hosts.php
https://setiathome.berkeley.edu/top_users.php
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robsmith
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Message 96398 - Posted: 4 Mar 2020, 9:00:46 UTC - in response to Message 96374.  
Last modified: 4 Mar 2020, 9:01:25 UTC

As I said a few months ago I can only give the very barest details for the 400kW system, no links, nothing like that, so you are going to have to suffer not seeing anything more than the scantest details. What I can say it is NOT in a domestic environment, and it does use the recovered heat to provide heating to other areas of the site.

And you demonstrate a remarkable lack of understanding about fluid dynamics.
You cannot consider a pump in a cooling circuit (well, a consumer one at least) as both pulling and pushing as you have things like pipework, expansion chambers, reservoirs etc. to consider.
Every heat exchanger has a working range for optimum heat transfer. Putting it simply, at low speeds one gets laminar flow, in the core, but the boundary layer can pool; only the boundary layers is in direct contact with the exchange-surface, and there is little mixing between the boundary layer and the core so you get poor heat transfer. Speed it up and get turbulence which results in mixing of the surface fluid and the rest and that gives you good thermal transfer; speed it up more and you get cavitation, which means the fluid is not in proper contact with the surface and you get less cooling and the potential for surface erosion.
There are some very simple tricks to induce turbulence into a flow, one of the simplest is the "static mixer" which sits in the pipe work and causes the fluid to tumble, a pair of intertwined coils, one with a clockwise twist and the other an anti-clockwise twist will do the job, as will a pair of half plates (semi-circular plates the same diameter as the pipe bore) with their straight axis perpendicular to each other between one and three pipe diameter apart.

The change in fluid velocity between the four and three GPU sets could be sufficient to move from laminar to turbulent flow hence the four would run hotter than the three. Ain't fluid dynamics fun :-)

Having the fans on a desktop PC either all pushing, or all pulling, is the simplest to understand, and will tend to be a bit better than having them mixed. However it is sometimes desirable to have one on the other side to get air into particular parts of the case without the need for ducting, which again can help but can be a real ***** to get right.

I gave up trying to work out why different countries so close to each other have such wildly different energy prices, there is no apparent physical reason, so it can only be down to political reasons.
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Ian&Steve C.

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Message 96403 - Posted: 4 Mar 2020, 15:43:06 UTC - in response to Message 96398.  

I gave up trying to work out why different countries so close to each other have such wildly different energy prices, there is no apparent physical reason, so it can only be down to political reasons.


has a lot to do with how the energy is generated too. areas that get power from hydro plants for example have almost free electricity no matter what country you're in.
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Profile Jord
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Message 96408 - Posted: 4 Mar 2020, 16:32:54 UTC - in response to Message 96384.  

Or a liar.
Please tone it down.

No messages intended to annoy or antagonize other people, or to hijack a thread.
No messages that are deliberately hostile, threatening, or insulting.

Discussion is fine, but do it in a civil way.
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Ian&Steve C.

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Message 96409 - Posted: 4 Mar 2020, 17:05:42 UTC - in response to Message 96408.  

and in the face of overwhelming evidence no less.
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Ian&Steve C.

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Message 96416 - Posted: 4 Mar 2020, 19:23:15 UTC - in response to Message 96411.  

No, they have a TDP of 250W, so 25 of them would be 6.25kW, less than an electric shower, quite capable of being powered in a household.

Why do you believe 10kW can't be fed to a house? Almost every house in the UK has a 240V 100A feed, which is 24kW, well more than enough.


even houses in the US have a 120V 100A service in most cases. (12kW), but not all of that is available to plug into the wall of course. but I'm using a 30A 240v circuit for the high power systems so his argument goes out the window anyway.

and your numbers being generous as well. only the RTX 2080ti has a TDP of 250W. I never claimed to have 25 2080tis, just that I had 25 RTX cards, which I do.

the Geforce RTX lineup ranges from the 2060 (160W) to the 2080ti (250W), or to the Titan RTX (280W) if you want to go that far (not counting the quadro cards). also not considering anyone's individual power limiting or overclocking.
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Ian&Steve C.

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Message 96418 - Posted: 4 Mar 2020, 20:07:07 UTC - in response to Message 96417.  

I'd say most existing and older average sized houses in the US have a 100A service. it's becoming more common for new construction to be fitted with 200A though.

Einstein is quite light on power needs. maybe 70-75% of stock TDP.
SETI and GPUGrid both will use full TDP (or whatever the power limit is set to) on most nvidia cards. Although I do have a couple GTX 1060s that have a totally unnecessary 200W TDP stock, but the card isnt even powerful enough to come close to that. SETI loads hover around 100W on that. but cards like my 2080s and 2080ti will use their full stock TDP limits under SETI and GPUGrid.
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ProDigit

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Message 96420 - Posted: 4 Mar 2020, 22:06:46 UTC

Here in Florida, you only get 2 phases (out of 3).
One for fridge, ac, washer and dryer, and kitchen, the second phase for the rest of the house.
And that's 50Amps (on 2 lines). The AC uses 30 amps out of the 50 max.
I get allocated a single outlet with a 15A breaker. On the wall, that's only 1440-1470W continuous, before the breaker trips.
That means we still have a good 30A for the remainder of the house. I don't think that's that bad.
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Ian&Steve C.

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Message 96422 - Posted: 4 Mar 2020, 23:15:30 UTC - in response to Message 96421.  

Some places also use natural gas for things like cooking, hot water, or even clothes dryers. you can get away with little electric use, especially these days with LED lighting. My parents living room has two 8-bulb chandeliers. They used to have 40W incandescent bulbs. that's 640W just for lights in one room. I recently replaced them all with 4W LED bulbs, ~64W with the same light output.
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ProDigit

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Message 96425 - Posted: 5 Mar 2020, 4:58:01 UTC - in response to Message 96421.  
Last modified: 5 Mar 2020, 5:01:47 UTC

Here in Florida, you only get 2 phases (out of 3).
One for fridge, ac, washer and dryer, and kitchen, the second phase for the rest of the house.
And that's 50Amps (on 2 lines). The AC uses 30 amps out of the 50 max.
I get allocated a single outlet with a 15A breaker. On the wall, that's only 1440-1470W continuous, before the breaker trips.
That means we still have a good 30A for the remainder of the house. I don't think that's that bad.


That's absurd. I assume you're talking about 50 amps at only 120V. That's a quarter of what I can take in the UK. Ok, so in Florida not much required for heating, but still, a very small amount if you use electricity to cook. I used to use about 6kW just for computers, that would have maxed out your total house. Turn on a light aswell and oops, too much! Don't you have things like an electric shower? That uses 8kW. And a cooker, that's 7kW.

The AC is the biggest power draw.
The water heater is not that big, since it's Florida, and the tap water is 75+F. 7kW. The stovetop 1.5kW per burner. I never use it.
While FPL guarantees 50A per line, occasionally I've ran ac, water and microwave all at the same time (that's <45 kW on the first line) without needing more.

I still have the second line for PC, lights, tv, and all other ac socket tools.

All the bulbs are leds, and the TV uses <100W. The fridge averages at 54w. So they're pretty much negligable compared to the ac. Not sure what else I use in the house... 1200W vacuum cleaner? Perhaps 60W on Christmas decorations?
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Message boards : GPUs : PCI express risers to use multiple GPUs on one motherboard - not detecting card?

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