Doubts about NVIDIA SLi

[solidsnake1607]

Hello everyone! Im planning to build a SLI Setup with two ASUS GTX 770 DCUII 2GB and this is going to be the first multi gpu setup ever for me. Lets start with the questions:
1-Both cards have 2GB of VRAM but combining two of them in SLI will give you only a total of 2 gigs for everything? I mean i know SLI does not duplicate the VRAM available but i wonder what happen with the 2gbs of VRAM of the second card! My main doubt is what happen if a game exceeds the 2 gigs.. Still the available memory in the second card wont be usable?
2-Why does the second card runs hotter that the first one?
-For SLI Setup is a recommended thing to change the thermal compund with another like Arctic MX4 in both gpus?
3-Is a SLI Setup of two 2gb 770's a futureproof choice for 1080p @120hz Gaming?

Thanks for taking your time to read my thread. Have a nice day. Regards

 

[Carfax83]

If I recall correctly, each card renders it's own frame separately, so they don't share VRAM. Don't worry about what the second card is doing, as long as there is GPU activity it's going to do it's job. Games will use whatever VRAM is available, and typically won't exceed your maximum amount. If your settings are too high, your game will just run really slow.

The second card (or top card) typically runs hotter because hot air is rising from the lower card. You can ameliorate this problem by making sure there is adequate cooling in your case, and that the cards have some space between them. On my machine, there is usually only a 2 or 3 degree delta between the top and bottom card, and that's only because I have a soundcard sitting right in front of the top card which blocks the air flow slightly.

I wouldn't change the thermal compound, unless your cards are running hotter than usual.

And two 770s should be good for 1080p gaming for a long time, especially if you have the overclocked models.

 

[solidsnake1607]

If I recall correctly, each card renders it's own frame separately, so they don't share VRAM. Don't worry about what the second card is doing, as long as there is GPU activity it's going to do it's job. Games will use whatever VRAM is available, and typically won't exceed your maximum amount. If your settings are too high, your game will just run really slow.

The second card (or top card) typically runs hotter because hot air is rising from the lower card. You can ameliorate this problem by making sure there is adequate cooling in your case, and that the cards have some space between them. On my machine, there is usually only a 2 or 3 degree delta between the top and bottom card, and that's only because I have a soundcard sitting right in front of the top card which blocks the air flow slightly.

I wouldn't change the thermal compound, unless your cards are running hotter than usual.

And two 770s should be good for 1080p gaming for a long time, especially if you have the overclocked models.

Each gpus renders its own frame separately. Interesting. Im really curious and and excited to try and see it by myself. Unfortunately i have to wait two weeks or more if i run out of money.
Yes the ASUS 770 is the selected edition and i do not plan to overclock the cards.. since they are going to be running together 1110mhz should be plenty to go above 60fps. Im curious if both can reach 120fps.
Yes dont worry about that. My casi is really cool. I have a Phantom 630 with four 140mm fan and 1 200mm as intake and two 200mm fan and one 140mm as exhaust. The cold days when i use the computer it feels even colder! Lol.

By the way the setup to pair the two 770s is:
-Sabertooth Z87
-Intel Core I5 4670 3.4GHz
-4x4GB DDR3 2133 C9 from Corsair Dominator Platinun series
-Seasonic Platinum 1000w PSU
-Samsung 840 pro 256 and two 1tb Caviar black in Raid0

Do you see any bottleneck for the sli setup? I picked that cpu because the i7 was too expensive and im not an overclocker so this was the cheapest option.

 

[Carfax83]

Your setup looks good. The cards will be running at 1110 base clock, but will probably boost to over 1200 MHz, so you shouldn't have to manually overclock them.

I would overclock the CPU a bit though, because SLI uses a lot more CPU power than single GPU.. You don't want to be CPU bottlenecked.

 

[solidsnake1607]

Your setup looks good. The cards will be running at 1110 base clock, but will probably boost to over 1200 MHz, so you shouldn't have to manually overclock them.

I would overclock the CPU a bit though, because SLI uses a lot more CPU power than single GPU.. You don't want to be CPU bottlenecked.

Unfortunately this cpu cant be overclocked. It can reach only 3700MHz with the 4 cores activated and 3900 with one or two. Really dissapointed. I used to have an i5 2500 non K and i could overclock it a bit further.
Ill comment my experience when i get the second gpu! Many thanks for your help, you ve been very helpful and you answered very quick! ^^

 

[Carfax83]

Oh I thought you had the 'K' version. If I were you, I'd return the 4670 and get the 4670 K, which you can overclock. I don't think you'll have poor performance with the 4670 non K, but having a CPU overclocked to at least 4ghz would definitely be beneficial. With a 4670 K, you should easily be able to hit 4.2ghz which is modest, but would increase your performance substantially.

 

[BallaTheFeared]

A non OC'ed CPU, even the fastest gaming cpu on the market, will prevent you from 120Hz gaming in a lot of titles.

 

[solidsnake1607]

Well that sucks.. I thought this thins was enough. What a bad surprise. Tell me another thing. Is really necesary to get 120fps in a 120HZ monitor ? With the single 770 i get about 50-80fps in demanding titles like bioshock infinite crysis 2 and a few other and i don see problems at all however i never reached 120fps not even close. A second 770 will give any noticeable boost then ?

 

[solidsnake1607]

Oh I thought you had the 'K' version. If I were you, I'd return the 4670 and get the 4670 K, which you can overclock. I don't think you'll have poor performance with the 4670 non K, but having a CPU overclocked to at least 4ghz would definitely be beneficial. With a 4670 K, you should easily be able to hit 4.2ghz which is modest, but would increase your performance substantially.

Now i want to sell my 4670 if this little bitch causes high bottleneck to the second gpu it will fly through the window really high to teach this bastard to go higher

 

[Carfax83]

Well that sucks.. I thought this thins was enough. What a bad surprise. Tell me another thing. Is really necesary to get 120fps in a 120HZ monitor ? With the single 770 i get about 50-80fps in demanding titles like bioshock infinite crysis 2 and a few other and i don see problems at all however i never reached 120fps not even close. A second 770 will give any noticeable boost then ?

No, it's not necessary to get 120 FPS on a 120hz monitor. I doubt you would even notice the difference between 120 and 60 FPS.. A second GTX 770 would also increase your frame rate substantially, but the CPU you have would limit your increase.

Whenever you go multi GPU, you should always make sure you have a fast CPU to help feed the GPUs. And since you're playing at 1080p which isn't exactly a high resolution by today's standards, you will be CPU bottlenecked for sure.

 

[solidsnake1607]

No, it's not necessary to get 120 FPS on a 120hz monitor. I doubt you would even notice the difference between 120 and 60 FPS.. A second GTX 770 would also increase your frame rate substantially, but the CPU you have would limit your increase.

Whenever you go multi GPU, you should always make sure you have a fast CPU to help feed the GPUs. And since you're playing at 1080p which isn't exactly a high resolution by today's standards, you will be CPU bottlenecked for sure.

In that case the smart option would be to save money, stay with a a single 770 until i go under 60fps and wait for the GTX 880 may be ? I dont really need the boost im just curious about SLi experience

 

[DooKey]

Stay with a single card until it doesn't offer the performance you want in the games you play.

SLI is good if you are looking for max frames with max eye candy.