Dual x16 vs Dual x8 mobo

[zaft1g337]

Hi. today i was looking around on some mobos when i came over some which had dual and even tripple x16 pcie 3.0. The weird thing is that many of these mobos were not THAT popular which mad me wonder why. Wouldnt that give 2xperformance compared to the usual dual x8 pcie?

I was thinking of the asus maximus v extreme with the 3770k cpu for my new gaming build, but right now im thinking of asus rampage iv extreme/formula with the 3820 cpu bcuz of the quad x16 pcie. Now i know that ill be sacrificing a good gaming cpu, but does it really matter that much since i wount be doing extreme oc'ing? ill probably be upgrading the cpu in two years or so to 3930k and also getting new dual (perhaps tripple) gpu.

I wont be doing wc at the beginning (have tight budget) but have plans for that in the future. Also im thinking of getting evo 212 so i can get a good psu like ax860i and upgrade the cooler later on since i wont be oc'ing at first.

I dont know how that sounds, generally im just thinking "loud" atm =) oh, btw the reason for choosing asus is that i want my build to be red/black/white and in norway we mostly only have asus, gigabyte and msi mobos.

 

[PingPangBV]

Hi there fellow Norwegian =)

It sounds like you believe you will have double performance from PCIE 16x ve PCIE 8X. Well that's very far off the real facts, what PCIE 16x and 8x represents is the bandwidth-not performance. Yes it is true that you get double bandwidth by using 16x vs 8x but you will hardly see any performance difference in either games or benchmarks.

For a gaming rig you won't ever need to go 2011, go for a Z77-board and a 3770k, well even the I7 3770k would be overkill for a gaming rig. You could save more money by going for an I5 3570K.

 

[zaft1g337]

Hi there fellow Norwegian =)

It sounds like you believe you will have double performance from PCIE 16x ve PCIE 8X. Well that's very far off the real facts, what PCIE 16x and 8x represents is the bandwidth-not performance. Yes it is true that you get double bandwidth by using 16x vs 8x but you will hardly see any performance difference in either games or benchmarks.

For a gaming rig you won't ever need to go 2011, go for a Z77-board and a 3770k, well even the I7 3770k would be overkill for a gaming rig. You could save more money by going for an I5 3570K.

then whats the point of having x16 bandwidth? :headscratch: isnt it for better performance? :sad:

 

[SnW]

For the later batch of GPU´s,
x16 vs x8 even x4 makes hardly a difference in games. in regards to FPS........

Ray.......

 

[dragoonk]

You would be better off with the 3570K, no need to go extreme, As for the PCi-e x16/x8 performance difference, I agree with PingBangBV and SnW

 

[XANADV]

There is one thing you should know in regards to PCIe bandwith. An LGA1155 socket CPU provides 16 lanes of bandwidth while LGA2011 provides 40 lanes. The lanes must be split between all connected devices, be they graphics cards, SSDs, RAID cards or whatnot. You mentioned the Maximus V Extreme, which is based on LGA1155. While that and boards like it have 4 x16 slots the CPU is not actually providing more than 16 lanes. No, the lanes on that mobo are being 'extended' by a PLX multiplexer chip. Think of that as a really fast switch if you will. What that does effectively is make your connected devices 'think' there are x8 or x16 lanes when in reality there are less than that being provided by the CPU. While that sounds good in concept the process creates some latency which makes such a board less than ideal for a gaming rig with multiple GPUs. I am personally very averse to such features though some people may say otherwise.

So my advice is this (assuming you are using your rig primarily for gaming): if you only plan on using one or two GPUs go with LGA1155 as PCIe will be split in x8/x8 natively. For this I would recommend you go with the Maximus V Formula (which I have in my own build BTW). If you are going with more than two GPUs then go with LGA2011. However I agree that you will be better served by going 1155 since you are on a tight budget.

 

[zaft1g337]

First of all, i want to thank everyone that replied.

You mentioned the Maximus V Extreme, which is based on LGA1155. While that and boards like it have 4 x16 slots the CPU is not actually providing more than 16 lanes.

Secondly i think u have ur facts wrong about maximus v extreme. They dont have 4 x16 (maybe if u only use one of them, but that i dont know and is not what im talking about) they have 5 (x16 or dual x8 or x8/x16/x8 or x8/x16/x8/x8). Also does that mean even if u have 3970x it would still not be able to provide sufficient lanes? If so, is there a point in having dual or quad x16 at all?

So my advice is this (assuming you are using your rig primarily for gaming): if you only plan on using one or two GPUs go with LGA1155 as PCIe will be split in x8/x8 natively. For this I would recommend you go with the Maximus V Formula (which I have in my own build BTW). If you are going with more than two GPUs then go with LGA2011.

Ill have 2 or 3 gpus its like 60/40 %. But ill start with 1 cuz of my budget, then increase the gpus later on. Also ive found out that dual 7970 have approx 5-10% lower fps compared to dual 680, but the price differences are approx 30% cheaper for the dual 7970. That means more performance/cost value. Something else that just poped up in my head is that ill be using no more than 2x 24"monitors @ 1080p. Primarily due to space available on my desk.

 

[XANADV]

First of all, i want to thank everyone that replied.


Secondly i think u have ur facts wrong about maximus v extreme. They dont have 4 x16 (maybe if u only use one of them, but that i dont know and is not what im talking about) they have 5 (x16 or dual x8 or x8/x16/x8 or x8/x16/x8/x8)

You are right, there are physically five slots but you can't use them all in a multi-gpu scenario so for the sake of the argument there are effectively four.

. Also does that mean even if u have 3970x it would still not be able to provide sufficient lanes? If so, is there a point in having dual or quad x16 at all?

Your CPU will use all the lanes it has available (up to x16 of course) and split them out accordingly. And there is no point to having quad x16; in your case they would split into x16/x8/x16 if you plan on going with three gpus. One more thing to keep in mind is that AMD cards can work in x4 while Nvidia require at least x8.

 

[zaft1g337]

AMD cards can work in x4 while Nvidia require at least x8.

Really? That's news to me.

So basically what you're trying to say is that having a rig with triple gpus on a mobo with x16/x16/x16 is no different than a mobo with x8/x8/x8 when it comes to gaming?

There is another question I've been thinking about lately. Maybe I should make a new thread, but I'll see about that later on. I've been wondering if there is any difference between having a 4x4Gb ram and 2x8Gb ram considering the heat generated and the performance both oc'ed and non-oc'ed.
1) Isn't it logical to think that 4x slots generates 2x more heat than 2x slots?
2) Isn't it logical to think that 4x slots are more stable than 2x slots?
Have there been any tests about this somewhere?

 

[XANADV]

Really? That's news to me.

So basically what you're trying to say is that having a rig with triple gpus on a mobo with x16/x16/x16 is no different than a mobo with x8/x8/x8 when it comes to gaming?

There is another question I've been thinking about lately. Maybe I should make a new thread, but I'll see about that later on. I've been wondering if there is any difference between having a 4x4Gb ram and 2x8Gb ram considering the heat generated and the performance both oc'ed and non-oc'ed.
1) Isn't it logical to think that 4x slots generates 2x more heat than 2x slots?
2) Isn't it logical to think that 4x slots are more stable than 2x slots?
Have there been any tests about this somewhere?

Nope no different between x8 and x16 as long as we're talking about PCIe gen 3. Even gen 2 won't be fully saturated yet unless you run 4 current gen GPUs.

I don't know enough about memory to give you valid answers to your questions regarding that but if I had to guess:
1)I'd say both 4x4GB and 2x8GB generate about the same amount of heat because they are effectively the same density, BUT there's more room for air to flow between 2x8GB DIMMs so those might run cooler.
2) They will both get the same stability unless you run a considerable overclock, in which case lower density DIMMs will have the upper hand.

Like I said I'm no expert on that subject so if I'm wrong somebody will correct me surely.

 

[XANADV]

@zaft1g337


Sorry, forgot to answer your last question. See if these might help.

http://www.xbitlabs.com/articles/memory/display/lga2011-ddr3.html
http://www.xbitlabs.com/articles/memory/display/ivy-bridge-ddr3.html

 

[Bang]

There are three types of pcie16, 16, 8 and 4x. 4x is generally for soundcards or other peripherals.

The motherboards with 2 or more 16X slots are generally pcie 2.0.
Since pcie 3.0 has twice the bandwidth of 2.0 it doesnt matter if your cards are run at 8x when two slots are populated.