Multi GPU over thunderbolt?

[tomaatvk]

Several days I got my laptop for university (an HP zbook studio g3) and it has an i7 6700HQ, a quadro M1000M and 2 thunderbolt 3 ports.

So I started thinking, what if I just buy something like a razer core and throw a GPU in there to have some gaming horsepower (because the quadro M1000M performs equally in games to a 950M).

But the laptop has 2 ports and I know thunderbolt 3 carries 4 PCI-e 3.0 lanes.

Now my question is, what if I were to buy 2 razer cores and throw 2 RX 480's in there, could I run them in Crossfire?

 

It has to be crossfire as SLI needs 8 lanes on each GPU and a bridge while crossfire can run with 4 lanes without a bridge.

 

This is purely out of curiosity, I am not planning on actually running crossfire over thunderbolt 3, even if it were possible.

[dantayy]

The razer core uses USB Type-C.

[tomaatvk]

Just now, Ernest_L said:

The razer core uses USB Type-C.

I know, it uses thunderbolt 3 over USB type-C and it has 2 of those ports, which is why I asked.

[manikyath]

1 minute ago, Ernest_L said:

The razer core uses USB Type-C.

it more specificly uses before mentioned PCIe lanes the type C connector can provide.

 

on topic: with the state GPU docks are in right now, i doubt anyone could give a conclusive answer to this (probably even the folks at razer and/or amd themselves), but i can tell you that if it works it'll probably not be the smoothest experience

[Misanthrope]

SLI over 4x max pci-e would be less than ideal. The external set up introduces little, but some latency to the system as well. Last (but not least) I don't necessarily think that having more than 1 thunderbolt port means you have more pci lanes specially on a laptop: that'd mean you're in X99 territory with the amount of lanes and it sounds very unlikely so it would probably be 2x + 2x pcie lanes to SLI/Crossfire over thunderbolt...so not there yet I believe.

[tomaatvk]

2 minutes ago, manikyath said:

it more specificly uses before mentioned PCIe lanes the type C connector can provide.

 

on topic: with the state GPU docks are in right now, i doubt anyone could give a conclusive answer to this (probably even the folks at razer and/or amd themselves), but i can tell you that if it works it'll probably not be the smoothest experience

 

1 minute ago, Misanthrope said:

SLI over 4x max pci-e would be less than ideal. The external set up introduces little, but some latency to the system as well. Last (but not least) I don't necessarily think that having more than 1 thunderbolt port means you have more pci lanes specially on a laptop: that'd mean you're in X99 territory with the amount of lanes and it sounds very unlikely so it would probably be 2x + 2x pcie lanes to SLI/Crossfire over thunderbolt...so not there yet I believe.

I never imagined it to be a smooth and ideal experience, I'm just interested in wether it would work or not. I can imagine that even Razer wouldn't have an awnser to the question.

As for PCI-e lanes, the 6700HQ has 16 PCI-e 3.0 lanes, the internal GPU probably uses 8 or 4 (probably 8) meaning there are 8 left. Each thunderbolt 3 port would have 4 lanes left (as the laptop contains a regular sata SSD and it doesn't have a slot for PCI-e/PCI-e over M.2 SSD's). This does lead me to conclude that both the thunderbolt 3 ports DO have 4x lanes which would be enough for RX 480 Crossfire. Nvidia doesn't allow SLI over anything less than 8x lanes/GPU so that is why SLI was already out of the question to begin with.

[Misanthrope]

Just now, tomaatvk said:

 

I never imagined it to be a smooth and ideal experience, I'm just interested in wether it would work or not. I can imagine that even Razer wouldn't have an awnser to the question.

As for PCI-e lanes, the 6700HQ has 16 PCI-e 3.0 lanes, the internal GPU probably uses 8 or 4 (probably 8) meaning there are 8 left. Each thunderbolt 3 port would have 4 lanes left (as the laptop contains a regular sata SSD and it doesn't have a slot for PCI-e/PCI-e over M.2 SSD's). This does lead me to conclude that both the thunderbolt 3 ports DO have 4x lanes which would be enough for RX 480 Crossfire. Nvidia doesn't allow SLI over anything less than 8x lanes/GPU so that is why SLI was already out of the question to begin with.

Hmm. Well it could theoretically work. I'd be a headache for sure though over just getting a 1070 or a Fury instead. Let's assume you get it to work: remember all the cons we give to multiple weak gpu set ups vs single strong ones? Those would not only still be present but compound the issues specially latency and such.

 

But if you have a way of testing it out without great personal investment (and we're talking just 1200 bucks for the razer core boxes without any gpus in them) I'd be very interested to know the results.

[tomaatvk]

17 minutes ago, tomaatvk said:

This is purely out of curiosity, I am not planning on actually running crossfire over thunderbolt 3, even if it were possible.

 

1 minute ago, Misanthrope said:

Hmm. Well it could theoretically work. I'd be a headache for sure though over just getting a 1070 or a Fury instead. Let's assume you get it to work: remember all the cons we give to multiple weak gpu set ups vs single strong ones? Those would not only still be present but compound the issues specially latency and such.

 

But if you have a way of testing it out without great personal investment (and we're talking just 1200 bucks for the razer core boxes without any gpus in them) I'd be very interested to know the results.

See the top quote, I was never planning on ever doing it, I was just curious.

If I would even invest in a razer core I would probably just use my current desktop GPU (GTX 780) for the laptop and get a new GPU for my desktop.

 

I would love to test it out but is seems rather impossible. It's not just that it would set me back roughly €1600 for the cores+RX 480's but it's also impossible to obtain a razer core inside the EU, if I go to the razer core page on the Razer Store it redirects me to the homepage of the Razer Store and there is no store that has it. If I were to set the store to USA I can get on the page of the razer core but I would have to pay someone to recieve the Cores and ship them over to the EU. This would probably add some more money to the bill and if you also count import taxes it would cost me ~€1800 which is a bit too much for just an exeriment.