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2 770's in SLI, maximum clock speeds are different?

Last response: in Graphics & Displays
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January 28, 2014 11:56:16 PM

Okay, so I know both of my cards either lower or boost their clock speeds depending on the needs of the game I am playing in order to balance between power consumption when the extra torque is unnecessary, and boosting above their standard clock speeds when every ounce of power is needed to maintain a stable framerate (The cards are factory OC'd, I haven't overclocked the manually). The advertised clock for both cards is 1137Mhz, during a cinematic or menu screens for some games, both cards usually clock down to 135Mhz @ 5%-ish, and then once I get back to the action, the game kicks back up to the necessary speed (different for every game, depending on how demanding it is).

Now my question is as follows: I notice that in very demanding games (Crysis 3, Metro: Last Light, etc.) The cards kick themselves up to their very maximum clock speeds in order to perform as well as they can, but I notice that the 1st GPU seems to cap out at 1215Mhz, but the second GPU seems to cap out slightly higher at 1247Mhz. I also noticed when I ordered the second card and it arrived, it was slightly different than the first. They're both the Gigabyte Windforce GTX 770 4Gb edition, but the first card has one 8-pin power connector and one 6-pin power connector, but the second card has 2 8-pin power connectors. Does the amount of connectors have any impact on the card's maximum voltage & clock speed? The cards are factory overclocked, I haven't pushed them any higher myself, but I found this rather odd. The second card is also set at the PhysX processor, so could that be the reason why the second card pushes itself further than the first? I have no issues with performance, every single game I've played so far has run at a buttery smooth 60FPS on the highest settings, but I don't know a whole lot about voltage & overclocking, so I'm trying to figure out whether or not I should consider switching my second card into my first PCIE slot and putting the first card in the second slot once it comes time to get into manual overclocking, unless it makes no difference that the second card seems to perform better than the first?

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a b Î Nvidia
a c 120 U Graphics card
January 29, 2014 12:26:24 AM

The PCI-E slot is rated up to 75W.
A 6-pin PCI-E connector is rated up to 75W.
An 8-pin PCI-E connector is rated up to 150W.

This means technically the card with 6-pin+8-pin connectors allows up to 300W and the card 8-pin+8-pin connectors allows up to 375W.
The GTX 770 has a rated maximum power of 230W from Nvidia. Neither of these cards will get near 300W so the different connectors don't matter.

Each different GPU manufactured can get to a slightly different speed.
The slot used can make a difference if they operate at different bandwidths (x16 + x16, x8 + x8 or x16 + x4).
Avoid using a slot operating at x4 if you can.

Swapping cards between the slots probably won't make much difference, but there is no harm in trying.
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a b U Graphics card
January 29, 2014 12:27:49 AM

It is not SLI if one card set as physix dedicated.. In SLI mode both card run's on same speed capped by the slowest card. If not in SLI every card can run at it own speed.

UPD: Try to enable SLI in NVidia control panel, disable PHYSIX, update drivers to the latest one, make clean install, make sure You do. Then check Your clocks. They should be the same, capped by the lowest, of course You should try to OC one of the card to make them equal for best performance.
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January 29, 2014 5:29:03 PM

NoOneLt said:
It is not SLI if one card set as physix dedicated.. In SLI mode both card run's on same speed capped by the slowest card. If not in SLI every card can run at it own speed.

UPD: Try to enable SLI in NVidia control panel, disable PHYSIX, update drivers to the latest one, make clean install, make sure You do. Then check Your clocks. They should be the same, capped by the lowest, of course You should try to OC one of the card to make them equal for best performance.


I am well aware how SLI works and how to install/uninstall/reinstall drivers. Neither of the cards are DEDICATED to PhysX, they ARE running in SLI, but one card IS set as the main processor for PhysX. In the Nvidia Control Panel, under the "PhysX settings" to the right of "SLI configuration" there is a dropdown menu where you have to select your PhysX processor, in my case the choices are: "Auto Select", "GeForce GTX 770 (1)", "GeForce GTX 770 (2)", and "CPU". "GeForce GTX 770 (2)" is the one selected as the PhysX processor, I.E. it takes the main load whenever PhysX is present in certain games, often causing the second card to run at a higher load than the first in less demanding games like Borderlands 2 or Mirror's Edge whenever cloth PhysX or glass particles get thrown around (One card clocks down to like 797Mhz or something and the second one runs at a slightly higher 800-something Mhz). I have Afterburner on in every game I play, and I can see the difference in the numbers when the cards are in SLI and when 1 card is dedicated to PhysX. My question was asking whether or not in certain games when both cards were pushed to their absolute limit, was the fact the second card was handling PhysX on top of the usual SLI load the reason as to why it boosted itself to a higher clock than the first. If the second card was DEDICATED to PhysX, it wouldn't be supporting a 70%+ load @ 1247Mhz in a game, it would be FAR lower as it's only processing PhysX, rather than rendering everything else alongside the first GPU.
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January 29, 2014 5:33:14 PM

Gah, I hit the wrong solution button, i meant to select VincentP's answer as the solution. Is it possible to change this? There doesn't seem to be any way I can personally undo my selection =/
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a b Î Nvidia
a c 120 U Graphics card
January 29, 2014 10:36:06 PM

thundagawd said:
Gah, I hit the wrong solution button, i meant to select VincentP's answer as the solution. Is it possible to change this? There doesn't seem to be any way I can personally undo my selection =/


I clicked the "Unselect this solution" link.
Does this allow you to select a new solution?
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January 31, 2014 1:05:43 PM

VincentP said:
thundagawd said:
Gah, I hit the wrong solution button, i meant to select VincentP's answer as the solution. Is it possible to change this? There doesn't seem to be any way I can personally undo my selection =/


I clicked the "Unselect this solution" link.
Does this allow you to select a new solution?


Ah yes, that solved the problem, thank you very much!
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