External GPU

What's holding the big GPU companies back from making an external GPU? Is it a tech issue that I'm not seeing? Couldn't you just put another port in the side?

It would do wonders for cooling solutions...Unplug it when you're on the go and not gaming, plug it back in when your at your desk.

 

External GPUs are hard to make becasue the bottleneck lies in the speed of the connection you get to the mobo from the GPU - you really need to match PCI bus speeds or higher. This is VERY difficult to attain with the current methods.

 

There is a rumor going around that the next generation DX10 high-end cards might be external....

 

Beats me, I would really love a DX10 one. Mabey they're just waiting to release them with DX10 cards. My system is has everything of a gaming system, its just lacking a good GPU. It would be great if they had external enclosurs where you could swap out and upgrade your card using a desktop one. Kinda like an external hard drive enclousre. Now my question is how would they connect it to a laptop. An ExpressCard adapter? 1394 port? Do either of these ports have sufficent bandwidth close to a PCI-E 16x?

 

Becasue ExpressCard talks straight to the mobo via speeds close to PCI-E, it may provide a viable option

http://www.expresscard.org/photos/expresscard-cardbus-hi.jpg

 

So gautam3 would you expect them to connect via the ExpressCard slot, or a 1394 port?

 

Well PCI Express can transfer at 4GB/s, Express Card's can transfer 500MB/s and FireWire 800 is 800 Mb/s, and most notebooks have FireWire 400 at best and usually none. So input is the problem. They would need to come up with a fast connection.

 

ExpressCards - not Firewire. Expresscard is also limited to its cap - but I would doubt it is 4GB/sec as another has noted. If this is truly so, it is theoretical, and for desktop PCI-E.

 

I just looked up Express Card speeds. They can do 2.5GB/s. That is if its internally connected using PCI-E. If its internally connected with USB 2.0, then the speed is 480mb/s. So if an express card can do what about 60-65% of the speed a normal PCI-E 16x can do, the yeah it could be done that way. It would be an interface inbetween PCI-E and AGP, but still better than most cards that come in laptops.

It is confirmed that they are doing this in the future right?

Just looked up 1394 ports, they only do 400mb/s, thus the name Firewire 400. So I guess thats out.

 

PCI-E is 250 MB/s per channel. A graphics card uses PCI-E 16x which is 16 channels and therefore 4GB/s. Express Cards use PCI-E 1x which is 250MB/s, no where near the 4GB/s that 16x can achieve.

 

Not according to this.

14. How is ExpressCard technology different from PC Card?
ExpressCard technology draws upon many of the features of existing PC Card technology. It balances size and utility, reliability and durability, and features hot plug-n-play and auto-configuration.

There are also significant differences between the PC Card standard and ExpressCard standard.

1. Size. ExpressCard modules are roughly half the size of PC Card, as well as being lighter (34 or 54 mm x 5 mm x 75 mm for ExpressCard vs. 54 mm x 85.6 mm x 5 mm for CardBus). See side-by-side comparison here.
2. Speed. ExpressCard modules use serial (PCI Express and USB 2.0) data interfaces rather than the ISA (16-bit PC Card) or PCI (CardBus) parallel bus interfaces, improving bus speed in data transfer while reducing the number of signals needed in the interface (2.5 Gb/s [PCI Express] or 480 Mb/s [USB 2.0] for the ExpressCard interface vs. 132 MB/s maximum theoretical throughput for the CardBus interface.)
3. Cost. Because of its streamlined system and mechanical design, ExpressCard designs are anticipated to have a lower implementation cost. Additionally, existing PCI Express and USB 2.0 silicon implementations can be repackaged into ExpressCard modules.
4. Less power. ExpressCard modules require less power than has traditionally been required.
5. Ease of use. ExpressCard modules offer a much easier method for installing new capabilities in a desktop computer because it eliminates the need to open the CPU chassis to add functionality (sealed box computing). In addition, it is hot-swappable between mobile and desktop systems, another plus for end-users.
6. Connector. 26 contact, single row beam-on-blade for the ExpressCard interface vs. 68 contact, dual row pin-and-socket for PC Card/CardBus.
7. Power supply. 3.3 V and 1.5 V for the ExpressCard interface vs. 5.0 V and 3.3 V for PC Card/CardBus
8. Host Interface. ExpressCard interface signals are supplied by host's base chipset where PC Card/CardBus requires a CardBus controller chip in addition to the host's base chipset.
9. Scalability. The ExpressCard interface is intended to extend to the next generation of both PCI Express and USB, where CardBus will not be extended beyond the existing interface.

 

I stand corrected. The most I had seen was 500MB/s. Still 2.5 is just a little more than half of PCI-E 16x.

 

Yeah but AGP 8x has a speed of 2gb/s, so like I said its in between AGP and PCI-E, but still 2.5gb/s is stll fast enough to give a good amount of graphics power.

 

Very true, and from what I have heard AGP was just recently actually maxed for bandwidth, and PCI-E is not even close to maxing out. I would love a new graphics solution since I think they are getting out of control with heat and power consumption.

 

Guys, you are mixing up megabytes and megabits.

Expresscard has a 2.5Gb BW, PCI-e 16x has a 5G B BW, or 16 times the bandwidth.

 

Regardless of any mix-up, I think the point is that the ExpressCard port is the only possible way an external GPU might be added to a system. Even with these predicted numbers, the actual values are usually a third or less, for various other reasons.

 

The BW of an Expresscard slot is simply not enough. It's 2,5Gb/s, or roughly twice the PCI bandwidth. There may be a connection for an additional screen there one day, but not much more.

 

Even if there was an external solution, you'd need a whole new laptop to use it. As has been said you're confusing Giga bits with Giga bytes, so the Expresscard slot is not even close to matching AGP speeds, never mind PCIe x16 that graphics cards use. There's currently no way to deliver the sort of bandwidth that PCIe x16 requires through a wired solution. It'll probably happen in the future but by that time the industry may have moved onto a much faster standard for graphics cards, so its a lot harder than one would think.

 

Yep good point.

Yes 2.5Gb/s (Gigabit per sec) = 312MB/s (Megabytes per sec). So the bandwidth is definitely not enough.

 

Why not just extend the "plug" on the mb to one of the notebook sides and call it a port? Put a plastic box around the card and make a cord that attaches to the port....

With the right equipment, it sounds like a 2 hour project to me....

 

In order for this to work, chris2pher71 is right, you'd NEED another "port" on the laptop. This port would be basically an "external" PCI-E slot (or whatever the standard is). Otherwise, there's no way to attain speeds for a graphics card. Even if you could, it would need more power than those slots can provide, and wouldn't perform near as well as low-end cards right now.

 

How about a USB Port, Firewire Port, and Express Card port combined?

Power Supply can be external.

 

Ok thanks for clearing that mix up. So once again it looks like the 1394 port is actually faster than ExpressCard, but still not fast enough. So if there is no real way to effectivly connect an external graphics card, why are they going to do it?

 

Read the first post, its just me asking why the HAVENT

 

I thought that they were, I remember reading a thread a week or two about this topic and they showed a prototype.

 

oh, really?

didn't know that. and here I was seeing my market niche....

 

Even though Firewire has greater bandwidth, it doesn't have anywhere near the low latencies required for a 3D graphics card, so that's out of the question. USB is even worse.

For some reason, I get the feeling that no one here seems to understand that you still need to be able to display the graphics on the laptop's LCD screen... yes - that's right, you need another interface to pass the video back to the LCD and bypass the built-in graphics... that kind of stuff doesn't just get 'passed along' the PCI-Express bus.

The only option you have for getting an 'external' GPU is if one of the manufacturers decides to place the GPU onto a replaceable card - like an MXM board. Even then, it's not likely to be 'external' more than it would be a replacable plug-in module that fits into a large hole in the laptop.

 

Express cards actually transfer at 2.5Gb/s (gah just read the rest of the posts)

Anyway that would be the best method USB and firewire dont even come close, They would be able to get around the bandwidth issue by compressing and decompressing the data as its sent. It would need a pretty major mobo revision for it to work though.

 

Firewire 800 is 800 Mbits per second NOT megabytes. If you don't believe me look here Therefore firewire can transfer at 100MB/s

No its Gigabits, not Gigabtyes. 2.5Gb/s is 314MB/s ( here is the proof)

In conclusion Express card is still the fastest, but sine it only operates on a PCI-e x1 lane, it is'nt fast enough at the moment to run Graphics cards.

 

Actually, the Firewire 1394b standard specifies a maximum speed of 3.2 Gb/sec... this certainly doesn't reach 800MB/sec, but it does reach 400MB/sec. Of course, no one that I know of has actually made such a product to date.

 

Ah yes so you are right, Firewire 1394b has a theoretical limit of 3.2Gb/s Firewire 800 has the limit of 800Mb/s

 

So if its theoretical can it be used?

Is 3.2Gb/s enough?

 

Nope 3.2 (G b/s) Gigabits per sec = ~400 (M B/s) Megabytes per sec is not enough.

Capital B is for Bytes. b is for bits...
8 bits in a Byte.