Trifire 7970s - Do I need NF200?

[Elfear]

Decided to pick up a couple more 7970s to mine bitcoins with and hopefully improve my gaming experience. I'm trying to decide which motherboard to buy since my current one only has 2 full-length PCI-E slots. I don't want to go crazy on a motherboard because Haswell will be out next year and I'll probably want to upgrade.

Going with the GA-Z68A-D3H-B3 will cost me $90 less than the Asus Revolution WS I am also considering. If I understand correctly, the Gigabyte would run three cards at x8 x8 x4 and the Asus would run three at x8 x8 x8 since it has the NF200.

That being said, according to this chart a x4 PCI-E slot will only decrease my performance by ~3% compared to a x8 slot.

Am I missing anything? Thoughts?

 

[Schmide]

Single slot 7970?

Not going to happen without water.

 

[Grooveriding]

The NF200 adds more PCIE lanes between the cards on the PCIE bus, but it also adds latency. It's important to note that no matter what you do on standard SB and IB there are only 20 lanes into the CPU. So the NF200 cannot do anything to overcome that bottleneck, you'll still only have 20 PCIE lanes communicating to the CPU.

There is a difference, particularly when you get into triple cards, the performance difference also becomes more apparent the higher the resolution you are trying to run.

I don't think you'll notice all that much though. Maybe you lose 10% or so vs using X79.

 

[Elfear]

Single slot 7970?

Not going to happen without water.

All three will be under water.

The NF200 adds more PCIE lanes between the cards on the PCIE bus, but it also adds latency. It's important to note that no matter what you do on standard SB and IB there are only 20 lanes into the CPU. So the NF200 cannot do anything to overcome that bottleneck, you'll still only have 20 PCIE lanes communicating to the CPU.

There is a difference, particularly when you get into triple cards, the performance difference also becomes more apparent the higher the resolution you are trying to run.

I don't think you'll notice all that much though. Maybe you lose 10% or so vs using X79.

I've read that the NF200 adds some latency but I didn't realize it didn't add any PCI-E lanes.

If 10% is the most I would lose, than I'm ok with SB. I'm leaning towards the WS Revolution right now since plumbing would be a pain with the Gigabyte board.

 

[Grooveriding]

All three will be under water.




I've read that the NF200 adds some latency but I didn't realize it didn't add any PCI-E lanes.

If 10% is the most I would lose, than I'm ok with SB. I'm leaning towards the WS Revolution right now since plumbing would be a pain with the Gigabyte board.

It could be even less now with IB supporting PCIE 3.0 I haven't seen any new benches done anywhere comparing if tri card setups overcome the PCIE lane limitation. I'm sure there is still a little performance drop off, but it could be even less now with IB and PCIE 3.0

 

[GotNoRice]

NF200? Isn't that unsupported old tech at this point?

The function has been replaced by newer PLX chips I believe.

One thing worth noting is that the first two slots (without PLX) will come from the PCIE lanes on the CPU, but the 3rd 4x slot will come from PCIE lanes off the southbridge. That means the 3rd slot is PCIE 2.0 even if you have an Ivy and your motherboard is otherwise PCIE 3.0 complaint. It also means some extra latency.

 

[RussianSensation]

Going with the GA-Z68A-D3H-B3 will cost me $90 less than the Asus Revolution WS I am also considering.

Are you sure there is enough room for 3 cards on that board? The 2nd and 3rd PCIe slots look awfully tight. I would say your biggest bottleneck will be the CPU and Tri-Fire driver scaling. There was a link recently showing 3x 7970 and the driver scaling is really bad. I wouldn't worry too much about PCIe 3.0 x4 when the third card often isn't even used in games or sometimes scales just 25-35%.

 

[Elfear]

NF200? Isn't that unsupported old tech at this point?

The function has been replaced by newer PLX chips I believe.

One thing worth noting is that the first two slots (without PLX) will come from the PCIE lanes on the CPU, but the 3rd 4x slot will come from PCIE lanes off the southbridge. That means the 3rd slot is PCIE 2.0 even if you have an Ivy and your motherboard is otherwise PCIE 3.0 complaint. It also means some extra latency.

That probably means some of the components that run off the Southbridge wouldn't work with Trifire. I don't want unusable Sata/USB ports running three cards.

NF200 seems the only option for 1155 boards if I need better PCI-E routing.

Are you sure there is enough room for 3 cards on that board? The 2nd and 3rd PCIe slots look awfully tight. I would say your biggest bottleneck will be the CPU and Tri-Fire driver scaling. There was a link recently showing 3x 7970 and the driver scaling is really bad. I wouldn't worry too much about PCIe 3.0 x4 when the third card often isn't even used in games or sometimes scales just 25-35%.

Ya, I think I spoke too soon with the Gigabyte board. It doesn't look like it would work very well trying to plumb the last two cards for watercooling. WS Revolution it is. Ivy Bridge or SB-E would cost twice as much at this point with the added cost of a processor.

I'd like to see a more recent review of Trifire using the newest drivers but I'm honestly not worried about the third card scaling all that well since mining will be it's primary job.

 

[n0x1ous]

That probably means some of the components that run off the Southbridge wouldn't work with Trifire. I don't want unusable Sata/USB ports running three cards.

NF200 seems the only option for 1155 boards if I need better PCI-E routing.



Ya, I think I spoke too soon with the Gigabyte board. It doesn't look like it would work very well trying to plumb the last two cards for watercooling. WS Revolution it is. Ivy Bridge or SB-E would cost twice as much at this point with the added cost of a processor.

I'd like to see a more recent review of Trifire using the newest drivers but I'm honestly not worried about the third card scaling all that well since mining will be it's primary job.

check out anands review on the asus z77 premium from last week. i believe there were some trifire benches in there

 

[NTMBK]

Of course, if you want buckets of PCIe bandwidth, there's always Sandy Bridge E...

 

[Pixelpusher6]

I currently own the Gigabyte Z68 D3H B3 and this board is entry level in every sense of the word. If you plan on overclocking it hits a ceiling at around 4.3~4.4Ghz on SNB probably because it only has 4 VRMs. Also the PCIe configuration is not 8x 8x 4x, rather it is 16x 4x or 8x 8x 1x. As soon as you have a 2nd card added the 3rd slot becomes only 1x. Probably the cheapest board you'll be able to get for tri-fire is the MSI Z77A-GD65 or GIGABYTE GA-Z77X-UD5H it lets you do 16x 8x 4x PCIe3.0/PCIe2.0 (PCIe 3.0 requires Ivy Bridge Processor, but will revert to PCIe2.0 with Sandy Bridge). I would say if you are really serious about getting the most performance from a tri-fire setup you are going to have to drop $250-300 on a motherboard such as Gigabyte G1.Sniper 3, EVGA Z77 FTW, P8Z77 WS, ASUS Maximus V FORMULA, etc. These will all have the new PLEX chip I believe which is really needed for tri or quad card setups. Since Z77/Z68 only provides 16 PCIe lanes from the CPU no matter what, the PLEX chip provides more PCIe lanes between each of the GPUs for GPU --> GPU communication. The PLEX chip is the new NF200, NF200 is now obsolete. Whereas the NF200 chip would only provide an additional 16 lanes @ PCIe 2.0 speeds, the PLEX chip provides up to an additional 40 lanes @ PCIe 3.0 speeds.

That chart you posted is a little misleading because the performance hit of less PCIe bandwidth can be more or less depending on the what is being run. Check out http://www.anandtech.com/show/5458/the-radeon-hd-7970-reprise-pcie-bandwidth-overclocking-and-msaa
Toward the bottom read about the affect of PCIe3.0 2x which is the same as PCIe2.0 4x. And that is just running 1 7970.

My recommendation would be if you are using a Sandy Bridge and don't plan to move to Z77 / Ivy then go with the ASUS Revolution WS with the NF200. If you do have an Ivy or plan to get one then it would probably be better to get one of the Z77 with a PLEX chip listed above. I've heard good things about the ASUS Maximus Formula V running tri or quad GPUs.

 

[RussianSensation]

I'd like to see a more recent review of Trifire using the newest drivers but I'm honestly not worried about the third card scaling all that well since mining will be it's primary job.

For mining, some guys get PCIe x1 to x16 cables to set up the cards without a case. Mining speed isn't affected much by PCIe bandwidth. So get the cheapest board that can run 3 cards and don't worry about PCIe since for mining shader speed is most important. For games it would be a different story though.

 

[Elfear]

check out anands review on the asus z77 premium from last week. i believe there were some trifire benches in there

Thanks for the heads up. I checked out the review and, for the limited games tested, it looks like Trifire is scaling better with newer drivers. Should allow me to run with SSAA at 1600p in all but the most demanding games.

snip

I do enjoy overclocking and the fact that the board switches to x8 x8 x1 basically eliminates it from the running.

I ended up getting the WS Revolution since it was the cheapest way to Trifire with decent performance. I'd like to save as much as possible for Haswell next year.

For mining, some guys get PCIe x1 to x16 cables to set up the cards without a case. Mining speed isn't affected much by PCIe bandwidth. So get the cheapest board that can run 3 cards and don't worry about PCIe since for mining shader speed is most important. For games it would be a different story though.

Now THAT is a mining operation!

I looked at the 1x to 16x adapters to use with my current Z68 board but I wanted near silence for my main rig since it sits 3 feet away from my head which means watercooling. Plus I do want the extra GPU power for gaming when needed.

If I set up a dedicated mining rig though, I'll be using a few of those adapters.

 

[Pixelpusher6]

Yea true if Bitcoin mining is your main usage then PCIe bandwidth doesn't really have any impact. I think you are going to have to spend a minimum of $200 for a board though. Even though there are boards like mine Gigabyte Z68 D3H B3 that have 3 PCIe slots, they are are not designed to run 3 GPUs. I don't think having 3 7970s pulling 225 watts over PCI Express will be well supported by only 4 cheap VRMs. I'm not even sure if the 3rd slot will recognize the graphics card when the other 2 are populated, I know you def. won't be able to crossfire all 3. This article talks about that http://www.bit-tech.net/hardware/motherboards/2011/07/14/gigabyte-ga-z68a-d3h-b3-review/1

It'd be much better to go with a board designed for more than 2 GPUs. I thought the Asus Revolution WS looked pretty good. Also check out the EVGA p67 ftw http://www.newegg.com/Product/Produc...82E16813188082
With support for 6 PCIe slots you have some room to expand and add another card or 2 in the future if there is room, perfect for mining. It's only $20 more. Those 2 are the best / cheapest I could find for what you are looking for.
I'm just curious have you ever thought about building a separate mining box with a cheap cpu and motherboard with a bunch of PCIe slots? I've seen people build boxes with older hardware that were effective
Also what is the price of bitcoins at now?

 

[Pixelpusher6]

Haha took me too long to type my response. Good choice on the Asus Rev WS, and you'll also have a spare PCIe slot if you decide to add a 4th card in the future from all your bitcoin profits! I've been thinking about starting mining but one thing that has me worried is the difficulty spike coming. Let us know how it all works out for you.

 

[RussianSensation]

Also what is the price of bitcoins at now?

> $12.50

http://www.bitcoincharts.com/markets/mtgoxUSD.html

 

[WhoBeDaPlaya]

> $12.50
http://www.bitcoincharts.com/markets/mtgoxUSD.html

And the odd part is it has been climbing steadily over the last week

For mining, some guys get PCIe x1 to x16 cables to set up the cards without a case. Mining speed isn't affected much by PCIe bandwidth. So get the cheapest board that can run 3 cards and don't worry about PCIe since for mining shader speed is most important. For games it would be a different story though.

Although to be fair, I've seen crazier FPGA setups

 

[RussianSensation]

Elfear, perfect timing for you to get reference 7970s and drop waterblocks on them.

CompUSA --> HD7970 for $360.

 

[Elfear]

Elfear, perfect timing for you to get reference 7970s and drop waterblocks on them.

CompUSA --> HD7970 for $360.

I picked up a pair of reference cards with full-cover EK blocks, the bridge, links, and backplates for $850 shipped. Considering grabbing one of the cards from CompUSA or TG and just running it stock. That would be ~2800MH/s.

 

[RussianSensation]

I picked up a pair of reference cards with full-cover EK blocks, the bridge, links, and backplates for $850 shipped. Considering grabbing one of the cards from CompUSA or TG and just running it stock. That would be ~2800MH/s.

You gotta update your sig! Stop being modest. What's the PSU driving them?

 

[Dark Shroud]

Those PCI-EX ribbons are a pain in the rear to deal with also linking PSUs together to the motherboard.

 

[RussianSensation]

Those PCI-EX ribbons are a pain in the rear to deal with also linking PSUs together to the motherboard.

He has 4 750W PSUs driving 4 motherboards with 4 GPUs on each. Doesn't look too complicated to be honest. Thing is though Butterfly Labs Jalapenos sounds tempting. $150 each ($163 with shipping). That's what I am contemplating about. Get those and wait 2-3 months or grab another 7970 for the time being.

 

[Elfear]

You gotta update your sig! Stop being modest. What's the PSU driving them?

Once I get the overclock nailed down I'll update my sig. Hoping for 1325Mhz on all three but that might be a little optimistic.

I'm running an Enermax Revolution 1050W PSU.

 

[RussianSensation]

Funny enough once 700W of power starts being used up, the costs really start to add up between a Bronze and a Platinum PSU.

700W actual / 0.82 efficiency for Bronze x 24 Hr x 30 days x $0.15 / kWh = $92.20
700W actual / 0.92 efficiency for Platinum x 24 Hr x 30 days x $0.15 / kWh = $82.17

$10 / month x 6 months = $60! Bitcoin mining is probably one of the few tasks where a Silver/Gold/Platinum PSU may actually be worth the extra cost long-term over the Bronze.

 

[DooKey]

Be careful when running bitcoin because those cards will be pulling lots from the slots. PSU 24pin plugs have burned up because of that. I'd buy a board that has an Aux molex to supply extra power to the PCI-E slots.