PLX chips being included on high-end Z97 boards

[Inaharry]

Hi,

I've noticed that a lot of the higher end Z97 motherboards have a PLX chip to allow 2-way SLI to run at 16x/16x or 3/4-way SLI, but I keep seeing things about how PLX adds latency.

I'm planning to use 2 x GTX 980 HOF cards in SLI and am unlikely to ever go to a 3-way setup, (unless I can get one really cheap in the future ). I know that the latency can be noticeable when using a single card which is why some boards like the MSI XPower have an additional slot for running single GPU solutions that'll bypass the PLX chip, but I can't find any benchmarks to find out how much of an impact using two cards in SLI on a PLX enabled board will make, all I've seen are figures for single cards and a justification for PLX to have 3/4 way-SLI on a Z97 setup, but no actual 2-way benchmarks.

It seems that if I want a high-end Gigabyte/MSI/Asus board with more features and decent on-board sound, the PLX chip is included by default.

Does anyone know whether the latency caused by the PLX chip when running 2 cards in SLI is noticeable as some of the benchmarks I found on single card setups show a couple of hundred points impact on 3DMark compared to boards without a PLX chip?

Thanks.

 

[Uncle Petey]

Well, I had no issues running benches and games with one, two or three cards enabled on a PLX board with a 2600K and my scores generally stood up well to the opposition when I did it.

I really wouldn't worry about it tbh.

 

[setter]

Do Asus even have a PLX Z97 board? On Z87 there was the Maximus 6 extreme, but that model was discontinued. Cant see it being much different with 2 cards tbh, I see similair bench/game results as others on here with PLX boards and dual sli.

 

[Inaharry]

Thanks for the feedback.

Do Asus even have a PLX Z97 board?

No, you're right. It looks like some of their WS boards have PLX, but not the ROG or TUF ones as far as I can tell.

I think I've narrowed down the choice to either the Gigabyte Z97X-Gaming G1, (not the Black Edition. I know that it goes through the extra testing, but I'd never use the Wifi or Bluetooth so it seems pointless paying extra for them) and the MSI Z97 Gaming 9 AC.

I like the audio on the Gigabyte and the layout of the x16 slots because there'd be much more airflow between the 2 GPUs. The audio on the MSI sounds good as well and it doesn't use a PLX chip which I don't really need for dual SLI as x8/x8 is supposed to be faster than the latency caused by the PLX, but space between the cards is less due to the x1 slot above the first x16 slot making the cards closer together and as the GTX 980 HOFs are just over two slots in size due to the fans, I'm not sure how hot they'll get in my Obsidian 650D because it doesn't have a side fan.

Audio is fairly important because I won't be installing my Xonar Essence STX into the new system and I'll still need an optical output for my Z906 speakers and a decent headphone output for a Sennheiser PC-360 headset.

My main concern with having a PLX chip is that there are so many articles and reviews that mention the latency, but it's accepted because it's the only way to have 3 or 4 way SLI setups running on an 1150 system. As I'm only going to have 2 cards installed, I don't want to degrade the performance unnecessarily, especially considering the extra cost of the HOFs to have guaranteed pre-overclocked cards only to lose performance because of the PLX.

I've been looking into this all week and am no further forward as to which board to go for.