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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Peter Hucker
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Message 96411 - Posted: 4 Mar 2020, 18:56:09 UTC - in response to Message 96384.  

It's your right not to believe things, but I've had all RTX GPUs (save for a 2080 Super). The brand makes less of a difference in terms of performance or overclockability, as they all get their boards from Nvidia, just differently binned.
Meaning, ASUS, MSI, EVGA,... all have about the same max GPU frequency depending on what bin they're getting their chips from (nowadays all are A+ or A++ something).
The only difference is in what ports, how many fans, how efficient the cooling is, etc...
So, yes, I did own all 6 RTX models released by Nvidia, spread out over all the brands. While I currently run 5 to 6 RTX GPUs, and own 15, I've owned a total of 25 RTX GPUs (counting the working ones, broken ones // Returns, and DOAs)


this only applies to the cards you have/had in your hands. certainly not ALL cards ever, and not all use cases either.

your gross simplification would be akin to saying something like "ALL CPUs can overclock to 5.3GHz because all of the ones I have did". It's simply not true in all cases.

But you'd admit at least that you haven't had 25 RTX GPUs, and thus have less of an authority on the topic, no?


No. I’m running 25 RTX cards right now. And have probably had my hands on ~20 more RTX or Turing cards through RMAs and just buying/selling different models. Not to mention the tons of different Pascal cards I’ve played with.

Current lineup
17x RTX 2070s
7x RTX 2080s
1x RTX 2080ti
1x GTX 1650
1x GTX 1050ti

Another 2070 on the way. A handful of Pascal cards that’s aren’t even running at the moment.

But I recognize that even having messed with a few dozen cards, it’s a small sample size compared to the millions that have been produced.


I'm guessing you're a lottery winner.

Or a liar.
To run 25 RTX GPUs simultaneously, you'd have to have an industrial building to feed them power, that's like several thousands of watts (if not 10kW)!
I'm sure he'd surpass the number one cruncher by now! XD


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.
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Peter Hucker
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Message 96412 - Posted: 4 Mar 2020, 18:57:53 UTC - in response to Message 96385.  

the flow path through the block is like so:


this is the way EKWB designed it. they are one of the biggest PC watercooling manufacturers. this is apparently "gen2" of this product. the one that they used in the LTT video had all 7 cards in parallel if I remember correctly. they obviously felt the semi-parallel design was better in one way or another. either way i can't complain about the temps. they are all pretty close.

this is a niche product though.


Presumably 7 in parallel was too much water and needed quite a big pump.
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Peter Hucker
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Message 96413 - Posted: 4 Mar 2020, 19:04:20 UTC - in response to Message 96398.  

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 just make them all push inwards. That way the chips that need the cooling are getting air blasted onto them, and I'm maximising the total air flow by having all fans working together.

I tried it on my main system recently - it was 4 fans, 2 in 2 out, then changed to all 4 in. The fans are temperature controlled. They all slowed down and I saw the CPU and GPU run cooler. There is adequate gap for the air to easily escape without an exhaust fan.

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.


Can't it also be down to where the power is generated and how much it costs to get the fuel there?
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Peter Hucker
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Message 96414 - Posted: 4 Mar 2020, 19:06:38 UTC - in response to Message 96403.  

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.


Hmph, the UK is one third wind power but it's most certainly not free. I guess we're still paying for installing them, maybe in the future it'll be cheaper. Unless the farmers get huge subsidies forever, which I wouldn't put it past the UK government to do.
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Peter Hucker
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Message 96415 - Posted: 4 Mar 2020, 19:11:45 UTC - in response to Message 96408.  

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.


It takes all sorts to make a world (as my grandmother once told me). I can't speak for Ian and Steve, but as for myself, anyone can call me any name they like. Water off a duck's back.
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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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Peter Hucker
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Message 96417 - Posted: 4 Mar 2020, 19:37:56 UTC - in response to Message 96416.  
Last modified: 4 Mar 2020, 19:39:57 UTC

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.


How do Americans manage with so little power? I thought you had a -120, 0, +120V split phase system, of about 100A, so the same power as the UK. And we can take most of that through outlets, and all of it with a little rewiring. Most houses have two 240V 30A circuits, plus another for the cooker (er.... stove, range) which usually has a socket next to it on the same circuit. Mind you, most people don't use computers in the kitchen - I did wire some of mine into that circuit at one point, they ran in the attic which was a bad idea, I had to install an air duct to get the heat out of there.

In my experience, TDP is a lot higher than real life usage anyway. I get close to TDP running Milkyway, but they use a lot less on Einstein.
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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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Peter Hucker
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Message 96419 - Posted: 4 Mar 2020, 20:16:01 UTC - in response to Message 96418.  
Last modified: 4 Mar 2020, 20:43:43 UTC

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.


But is that 100A at 240V? As I understand it you all have 120V and 240V (split phase), so you can get 100A twice at 120V.

I've heard that some parts of Italy only have 3kW for the whole house. They have problems using an electric kettle.

I was assuming Einstein uses less power on my cards than MW because it's single precision so uses a different part of the GPU core? On both projects I run two WUs at once to get maximum productivity.
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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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Peter Hucker
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Message 96421 - Posted: 4 Mar 2020, 22:29:58 UTC - in response to Message 96420.  

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.
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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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Peter Hucker
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Message 96423 - Posted: 5 Mar 2020, 0:06:11 UTC - in response to Message 96422.  
Last modified: 5 Mar 2020, 0:08:55 UTC

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.


In the UK they seem to allow for both. Natural gas is available in most places, but sometimes people use electricity for cooking and/or heating. All houses get the same 24kW electric supply whether gas is available there or not. Quite useful when you want the convenience of a powerful electric shower, or your gas heating breaks and you use electric heaters. Or like us you want to run ridiculous amounts of powerful computers at once. Or maybe you want to use an industrial welder.

As for LEDs, I've got 150W of LEDs in one room. They really aren't as bright as they claim to be. 10 times as efficient as an incandescent my arse. I'd say 5 was more realistic.
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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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Peter Hucker
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Message 96446 - Posted: 5 Mar 2020, 18:52:49 UTC - in response to Message 96425.  
Last modified: 5 Mar 2020, 18:54:49 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?


You say LEDs, but not long ago you would have had incandescents, with the same lines.

So I take it you get 50A on each of two *120V* lines. So that equates to about half of what I get in the UK. I think I would have blown the main fuse a few times. In the UK it's a fuse not a breaker, and they don't like you blowing it as they have to come out and change it. Although anyone with an ounce of common sense buys a new one on Ebay for a fiver and changes it themselves. If they ask "why is the tamper proof seal broken" I say "because I was working on my fuse panel and needed it shut off" (yes they have no main switch!!)

So, you could use the 7kW water heater (that is actually huge, most in the UK are 3kW) and cook a meal on all 4 burners, adding another 6kW. Then turn on the oven for presumably about 3kW, while someone is taking a shower at another 8kW. That adds up to 24kW. That's the UK limit, but twice yours. I've had mine up to 20kW in the past. And what happens if you happen to draw it all from one line?
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