PCI-E Lanes

[_kR15n]

I am Building a computer, yes for mining...

Intel E3 1275 V6 supports only 16 PCI-E lanes and i am planning to put 19 gpus in my Computer... I guessed that it wont work but better be sure than sorry so i am asking that here. Will it work or i need to put in a processor with atleast 19+ PCI-E lanes?

 

https://ark.intel.com/products/97478/Intel-Xeon-Processor-E3-1275-v6-8M-Cache-3_80-GHz

(Number of PCI-E lanes under Expansion options)

 

https://www.asus.com/us/Motherboards/B250-MINING-EXPERT/

(motherboard)

[NumLock21]

Consumer cpus only. Xeon will not work with a B250. The chipset will provide additional 12 lanes.

[_kR15n]

So any processor which is not Xeon like Pentium or Core will work?

[NumLock21]

7 minutes ago, CatCam1 said:

So any processor which is not Xeon like Pentium or Core will work?

Yes for socket 1151 only.

[TheGlenlivet]

All of the 6th and 7th gen CPUs that fit that board have 16 lanes (Except Celeron).  From i7 to pentium.

[vorponati0NN]

Nzxt x62
Asus maximus x hero
8700k
1070ti asus strix
Ram 16gb hyper x fury

 

Made for games and I have fps dropping issue can someone help/guide me ??

[TheGlenlivet]

1 minute ago, vorponati0NN said:

Nzxt x62
Asus maximus x hero
8700k
1070ti asus strix
Ram 16gb hyper x fury

 

Made for games and I have fps dropping issue can someone help/guide me ??

Start a new topic.

[NumLock21]

4 minutes ago, TheGlenlivet said:

All of the 6th and 7th gen CPUs that fit that board have 16 lanes (Except Celeron).  From i7 to pentium.

They all have 16 lanes including Celeron.

[TheGlenlivet]

5 minutes ago, NumLock21 said:

They all have 16 lanes including Celeron.

My bad, even the Celerons have 16.  Not sure what I was looking at that shows less.... maybe it was a mobile processor or something.

[mariushm]

The list of supported processors is here : https://www.asus.com/us/Motherboards/B250-MINING-EXPERT/HelpDesk_CPU/

 

Note that also you may get into issues like not being able to use more than 8 cards from same manufacturer, like maybe use 8 x RX 570 / RX 580 and 8 GTX 1060 / 1070

Don't buy that motherboard thinking you're gonna be able to use ALL those slots.

 

I'd also suggest you consider really hard what's the best power vs price for power supplies, maybe you'll find it's better off to have 5-6 video cards per motherboard and a single 650-750w power supply  instead of going with 1000w+ power supplies

 

For example, that Asus B250 mining expert is almost 300$ ...

You can buy this GIGABYTE GA-970A-DS3P motherboard with 5 pci-e slots for 76$ on Amazon .. so for 230$ you get 15 pci-e slots. and you only need to use 4 risers per card, saving your around 5$ per board. 

The processors are also super cheap, you can buy a Sempron 140/145 from eBay for less than 10$ each ( here's an example for 6.5$ from South Korea)and some 10$ coolers for these processors (here's example for 6$ on Newegg) also use DDR3 memory which is much cheaper, you can buy 2-4 GB sticks from eBay as well.

AND you can use ONE power supply for each 5 video card rig, let's say a 750-850w power supply will do if you go with GTX 1060 or RX 570 ... 850w if you go with RX 580 unless you try a bit of undervolting.

 

The only downside is taking more space on the shelves and maybe 50-60w more power consumption (since you have 3 motherboards instead of 1 and each board uses maybe 10-20w) and well, yeah, may have to spring for 3 hard drives instead of 1... but you can get refurbished drives for 10-20$ also. I can buy 80GB sata drives locally for 15$ ...

 

[NumLock21]

Just now, TheGlenlivet said:

My bad, even the Celerons have 16.  Not sure what I was looking at that shows less.... maybe it was a mobile processor or something.

Yes, mobile ones have less.

[_kR15n]

@mariushm what did you mean under "using only 4 risers per card"? dont you only need a 1x to 16x riser (only 1 per card)? 

 

Also why wouldnt i be able to use all 19 pcie slots:

(Reason im asking is the whited out text)

[mariushm]

Some video card drivers are designed to support a maximum number of devices. In the past, at least for AMD there was a hard limit set to 8 video cards, if you added more they wouldn't work or wouldn't be recognized. I know they removed this limitations in newer drivers but there can still be issues.

Then you have issues with operating systems not liking so many pci-e devices.. i don't know what to tell you, it may be perfectly fine, you may encounter bugs.

Then each video card needs some amount of memory (ram) to work properly and reserves some memory, something like 100 to 500 MB of memory, and for maximum compatibility with everything, all these chunks of memory should be reserved from the first 4 GB of memory installed on your motherboard. If you have 8 cards each reserving 200 MB of ram, you already have around 2 GB out of your 4 GB unusable.    

With 18 cards, you'd probably need to use at least 8 but probably 16 GB of DDR4 memory which adds to the cost. DDR3 is cheaper, and with 5 cards per system you'll probably be just fine with 2 or 4 GB of memory per system.

 

You also NEED three power supplies with that motherboard, because the motherboard uses the 12v wires from each 24 pin connector AND those 3 molex connectors on the edge to give power to the pci-e slots ... a video card is allowed to take up to 60w (on 12v) from the pci-e slot, so with 18 pci-e x1 slots, there's up to 1080 watts that have to go into the motherboard, through those 3 molex and 3 24 pin connectors, that's 3 circuits (1 12v circuit per molex) + 6 circuits (2 12v circuits per 24pin connector), so overal 9 circuits of 12v, and each of those can transfer around 100 watts safely, so at best you have 900 watts. You better hope each video card uses less than 900w / 18 connectors = 50w per slot.

You also have to be careful to plug one molex connector from each power supply into those edge molex connectors, so that the power draw will be even between the three power supplies.

My guess is that Asus expects you to undervolt all video cards, so that they use less power than normal from each slot.

You'd also be pretty much forced to use 3 power supplies rated for at least 1000-1200 watts, which are way more expensive than 750-850w power supplies.  (it depends on how many slots you eventually end up using out of the 18)

 

 

Now here's how it's much simpler with my suggestion..

You can have 4 or 5 video cards per system. You have just one power supply per system. With a full or medium tower case, you can probably have all 4 or 5 video cards within the case footprint. 

 

Here's how the board looks :

 

If you go with 4 video cards per system, you put two cards into the x16 slots and you lose one of the x1 slots, because the video card is tall enough to block that port. On the other two x1 slots, you install risers which look like this:

 

 

so instead of taking power from the motherboard, you give power to the pci-e slot from the power supply, either from a pci-e 6pin connector, or through a molex connector or a SATA connector.  The pci-e 6 pin or molex connector are best choices.

( If you're lucky, the video card cooler is designed in such a way that you may be able to squeeze the tiny pci-e x1 circuit board in that 3rd pci-e x1 slot and still be able to use it.)

The motherboard can easily power the two pci-e x16 slots from the 24pin atx connector and it's happy. The other three cards receive power directly from the power supply, the cable only sends data into the pci-e slots.

 

So for this 4 video card per system you'll simply need one power supply with 24pin atx + 4/8 pin cpu + 4 x pci-e 6+2 pin for video cards +  2 or 4 molex connectors and maybe one sata connector for a hard drive. 

The safest connection would be plugging a pci-e 6 pin connector from power supply into the riser, or to use a 2 x molex to pci-e 6pin adapter like the one below, and have each molex connector plugged into a different strip of molex connectors coming from the power supply (because 2 or 3 yellow wires is better than just one) :

 

 

 

If you go with 5 video cards per system, you'd have to pull out one of the cards so that it won't block the 3rd pci-e x1 slots, so you'll need 4 pci-e risers, one in all but the last pci-e x16 slot.  The power supply would only need a couple more molex connectors or worst case scenario you can use sata ports to power that 4th riser.

 

so drawing the line

 

~75$ for motherboard

~15$ for cpu+heatsink/cooler

~20$ / 30$ for 2-4 GB DDR3

~15$ for some refurbished HDD , 20-30$ for some 32-60GB SSD

~ 7$ x 2-4 for pci-e risers  (each)

~ 3$ x 2-4 optional for 2 x molex to pci-e 6pin adapters  (each)

~ 75$ and higher for gold efficiency 650w power supply, ~ 85$ for 750w psu

 

A cheap EVGA GQ (1000w gold efficiency) is 180$, more than twice as much as 750w-ish power supplies, and with smaller power supplies you could also afford to have some hot spares (if one psu dies just replace it with one on hand instead of having rig dead for days and ordering another 1000-1200w psu and then submitting the dead one to warranty)