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GT640 for PhysX - passive operation possible?

boxleitnerb

Platinum Member
Nov 1, 2011
2,597
1
81
Hi guys,

I would like to get a GT640 for PhysX. Problem is, I need it to be silent AND single slot. There is one passive cooled model out there, but that occupies 2 slots.

Is it possible to run a GT640 passively when it is only doing PhysX? I would assume that the GPU load would not be at 100%, but much lower, so it should be possible, shouldn't it?
 
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boxleitnerb

Platinum Member
Nov 1, 2011
2,597
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81
Because my GTX580 SLI is watercooled and my whole rig is silent.

Before anyone asks:
This setup is not enough. With PhysX at high I get asymmetric GPU load and fps drops to 45fps in Borderlands 2. With PhysX at low I get a steady 60fps. PhysX+SLI = not optimal. I could dedicate the second 580 to PhysX, but then I would have to cut back on the settings (SGSSAA), which I quite frankly don't want to do :)
 

toyota

Lifer
Apr 15, 2001
12,957
1
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um a gt640 a will actually slow down your system as opposed to letting the gtx580 sli run it. a gt640 will offer very little gain over having even a single gtx580 run physx and graphics.
 
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f1sherman

Platinum Member
Apr 5, 2011
2,243
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0
nah... PhysX works best with dedicated GPU, and GT 640 is likely ideal

incoming BL2 patch promises PhysX optimizations, so dedicated maybe won't be needed
 

boxleitnerb

Platinum Member
Nov 1, 2011
2,597
1
81
@toyota:
Are you sure? The GT640 has a hefty 700GFLOPs, the GTX580 1580 GFLOPs. With PhysX at low the GPU load on my GPUs can go up to 80% - there is not much room for PhysX calculations.

Problem I see is, that with SLI+PhysX, scaling is significantly worse in demanding situations than without PhysX.

The main question remains:
Will I be able to run the 640 passively? It would sit at the bottom of my case and would not get the heat from the other cards or the power supply (that sits in a separate compartment).
 

toyota

Lifer
Apr 15, 2001
12,957
1
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nah... PhysX works best with dedicated GPU, and GT 640 is likely ideal

incoming BL2 patch promises PhysX optimizations, so dedicated maybe won't be needed
no necessarily and this has been discussed over and over. 580 sli is most certainly faster than have a low end card for physx. again even with a single 580, using a 640 may not be much of an improvement.
 

boxleitnerb

Platinum Member
Nov 1, 2011
2,597
1
81
But that is only true when your GPUs have some headroom. I push mine to the limits in most games with SGSSAA, AO etc., so there isn't really much power left.

Kepler has much higher compute power (the number Cuda cores) compared to Fermi. As PhysX solely relies on that and not ROPs, TMUs or bandwidth, the GT640 is not that low end as one might think.
 

TheUnk

Golden Member
Jun 24, 2005
1,810
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71
Because my GTX580 SLI is watercooled and my whole rig is silent.

Before anyone asks:
This setup is not enough. With PhysX at high I get asymmetric GPU load and fps drops to 45fps in Borderlands 2. With PhysX at low I get a steady 60fps. PhysX+SLI = not optimal. I could dedicate the second 580 to PhysX, but then I would have to cut back on the settings (SGSSAA), which I quite frankly don't want to do :)
Censor your gore/blood and see what your fps drops to in most situations. I think the jelly has problems and lacks optimization. I can have it on high and the only time it dips below 60fps is when some other jelly appears like the green ooze. All the debris in the world with tons of cloth don't make a dent in my fps though.
 

PrincessFrosty

Platinum Member
Feb 13, 2008
2,301
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www.frostyhacks.blogspot.com
I would not make the assumption that load wouldn't be at 100%, it's never a good idea to have hardware which at risk due to the behaviour of software.

If there's no single slot passive coolers are you planning on getting an active cooler and simply disconnecting the fan? Or are you going to replace the cooling system entirely, in which case the best thing to do is find out the thermal dissipation of the heatsink you want to use and compare that to the thermal output of the card, I'm sure them numbers must be out there, if compatible single slot passive coolers exist.

With a decent passive heatsink and pretty decent case cooling I'd be comfortable with that given manufacturers are making passive cooling on 2 slots, but with a single slot active cooler with the fan disabled, I wouldn't risk it, too much space on the limited 1 slot heatsink will be wasted on the fan.

You could always try tweaking the 3D clocks to be slower to enforce safe operating temps at the sacrifice of speed, then once you're happy flash the new clocks onto the cards BIOS to mitigate the software risk.

I'd more likely go with a brand that has a very quiet fan, or instead of butchering clock speeds to get stable temps, instead just by a slightly slower card that does have 1 slot passive cooling off the shelf. A lot of it depends on your ambient temps and case cooling though, I personally wouldn't passively cool any decent video card in a case that has bad ambient cooling to start with.
 

toyota

Lifer
Apr 15, 2001
12,957
1
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http://www.geforce.com/Active/en_US/shared/images/articles/batmanarkhamcity/BAC-DX11-TessHigh-PhysXHigh-FXAAHigh-PhysXSecondaryCardComparison.png
um you do realize the base line there is a 560 ti dont you? he has 580 sli so what you just showed was not useful at all.
 

f1sherman

Platinum Member
Apr 5, 2011
2,243
0
0
But I'm not even arguing with you. You are so off that it's pointless.

That chart is straight from the horses mouth, and I left it here to be used at anyone's discretion.
Not as an continuation of argument with you :)
 

boxleitnerb

Platinum Member
Nov 1, 2011
2,597
1
81
I would not make the assumption that load wouldn't be at 100%, it's never a good idea to have hardware which at risk due to the behaviour of software.

If there's no single slot passive coolers are you planning on getting an active cooler and simply disconnecting the fan? Or are you going to replace the cooling system entirely, in which case the best thing to do is find out the thermal dissipation of the heatsink you want to use and compare that to the thermal output of the card, I'm sure them numbers must be out there, if compatible single slot passive coolers exist.

With a decent passive heatsink and pretty decent case cooling I'd be comfortable with that given manufacturers are making passive cooling on 2 slots, but with a single slot active cooler with the fan disabled, I wouldn't risk it, too much space on the limited 1 slot heatsink will be wasted on the fan.

You could always try tweaking the 3D clocks to be slower to enforce safe operating temps at the sacrifice of speed, then once you're happy flash the new clocks onto the cards BIOS to mitigate the software risk.

I'd more likely go with a brand that has a very quiet fan, or instead of butchering clock speeds to get stable temps, instead just by a slightly slower card that does have 1 slot passive cooling off the shelf. A lot of it depends on your ambient temps and case cooling though, I personally wouldn't passively cool any decent video card in a case that has bad ambient cooling to start with.
I want to spend as little money as possible. After all, there are not that many PhysX games out there.

Cooling conditions in my case are:
External radiator, about 25 degrees Celsius room temperature (winter is coming :biggrin:). Both 580s and my CPU are water cooled, so they don't really contribute to the "heat" inside the case. No HDDs, power supply sits in a seperate compartment on the bottom of the case. Pretty good conditions I would say.
 

toyota

Lifer
Apr 15, 2001
12,957
1
0
But I'm not even arguing with you. You are so off that it's pointless.

That chart is straight from the horses mouth, and I left it here to be used at anyone's discretion.
Not as an continuation of argument with you :)
I am off? you actually think a gt640 can do a better job at handling physx than gtx580 sli can at graphics and physx combined. that is nonsense. a gt640 is probably not much faster than a 9800gt so you are giving it way too much credit.
 

tviceman

Diamond Member
Mar 25, 2008
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514
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can you still run in sli but set physx to be calculated only on the second GPU (as opposed to running your second 580 as a dedicated physx)? I have read awhile back this helps with frame rates.
 
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f1sherman

Platinum Member
Apr 5, 2011
2,243
0
0
@toyota GT 640 would smoke both non-dedicated PhysX setup and 9800GT in Borderlands 2.

And even more so on SLI setup.

Mark my words, and lets revisit this in few days when benchmarks are available :)
 

boxleitnerb

Platinum Member
Nov 1, 2011
2,597
1
81
can you still run in sli but set physx to be calculated only on the second GPU (as opposed to running your second 580 as a dedicated physx)? I have read awhile back this helps with frame rates.
I'll try that, good idea.

Edit:
No change :(
 
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toyota

Lifer
Apr 15, 2001
12,957
1
0
@toyota GT 640 would smoke both non-dedicated PhysX setup and 9800GT in Borderlands 2.

And even more so on SLI setup.

Mark my words, and lets revisit this in few days when benchmarks are available :)
its a fact that based on benchmarks, a gt640 has about the same power as a 9800gt. well here is some reality for you. here you can see a gtx480 with different cards being used for physx. now factor in that a gtx580 is 20% faster than a gtx480. that would make the baseline about 60fps. so a gt640/9800gt level card would be below what that 9800gtx is given here in Mafia 2. and this with just ONE gtx580, with TWO gtx580s a freaking gt640 would be slower.


 

railven

Diamond Member
Mar 25, 2010
6,604
560
126
Well since the topic is PhysX and the GT 640 was mentioned...might as well ask here.

I was using a 9800 GTX+ which only has like 112 cuda cores (or something) and I'd tank when blood/liquid would fly about. Cloth/Debris, no issue.

Today I'll be getting my GTX 460 back from a friend, it has 336 CUda Cores (or something of the sort.) I'll be giving that a shot.

However, I was at the Microcenters and looking over the GT 640 AND GTX 650. So it seems for PhysX offloading the faster RAM on the GTX 650 would do nothing for PhysX offloading? Both have the same core count. [Mainly because they are smaller and cooler running versus the GTX 460, that and I'd probably sell off the GTX 460 or use it in another PC for 720P gaming.)

Do core clocks affect it or just core count?
 

toyota

Lifer
Apr 15, 2001
12,957
1
0
of course clocks affect it. if you had 400 cores at 800mhz then how would that be any better than 200 cores at 1600mhz? thats based on everything else be equal of course and using the same architecture. now kepler cores are not only lower clocked but they are way slower clock for clock too though.
 

f1sherman

Platinum Member
Apr 5, 2011
2,243
0
0
Core clocks x Count, ie total FLOPS

Plus architecture optimizations, ie I'm pretty sure 640 will be faster even if GTX 285 has more flops and is better at general compute simply because its more current.
 

railven

Diamond Member
Mar 25, 2010
6,604
560
126
of course clocks affect it. if you had 400 cores at 800mhz then how would that be any better than 200 cores at 1600mhz? thats based on everything else be equal of course and using the same architecture. now kepler cores are not only lower clocked but they are way slower clock for clock too though.
Sorry, not an avida nVidia user, so I really don't follow their CUDA core count and stuff as closely.

So, with that said, which would be better for PhysX Offloading:
GTX 460 SC vs GT 640 stock vs GTX 650 SC?

Off the top of my head, the 460 is clocked around 850mhz, the 640 was clocked like 980 or something, and the 650 was clocked 1058. The clocks aren't exact, but it's what I remember. The 640/650 both have 384 cudas vs the 336 of the 460.
 

toyota

Lifer
Apr 15, 2001
12,957
1
0
Sorry, not an avida nVidia user, so I really don't follow their CUDA core count and stuff as closely.

So, with that said, which would be better for PhysX Offloading:
GTX 460 SC vs GT 640 stock vs GTX 650 SC?

Off the top of my head, the 460 is clocked around 850mhz, the 640 was clocked like 980 or something, and the 650 was clocked 1058. The clocks aren't exact, but it's what I remember. The 640/650 both have 384 cudas vs the 336 of the 460.
the gtx460 will certainly be the faster card for physx by far.
 

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