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Hello,

I'm thinking of pairing my 650Ti with another low-mid card and I'm torn between the 750Ti and the 660. Their performance GPUGRID-wise is at about the same level, but I'm thinking maybe the 660's 50% wider memory bus gives it an edge over the 750Ti, at least for some types of WUs. On the other hand, the 750Ti's power consumption (60W) is less than half of the 660 (140W), greatly reducing power cost and heat emission. The purchase cost difference is ~15 euro for me, the 660 being the more expensive, and I don't find it a decisive factor. What do you guys say?

Also: my motherboard has its second PCIE-16 slot at 4x. How much would it affect the performance of my 650Ti?

Thanks,
Vagelis

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While the GTX660 is 5 or 10% faster, the GTX750Ti is the better card because it's newer (more future-proofed) and uses much less electric, which in turn generally means cooler, quieter and better for the rest of your system.

The 660 only has a 50% wider memory bus on paper. The 750Ti's cache size is larger and I think it's not as constrained as the previous generations due to the GPU's architecture. It's not super-scalar for a start.

If I were you I would consider selling your 1GB GTX650Ti (110W TDP) and getting two 2GB GTX750Ti's (60W).
The GTX750Ti is really an upgrade for the GTX650Ti, but does a lot more work (about 40% more).

The SP GFlops/W of the GTX750Ti is 21.8. The only Kepler's that come close to that are the high end GK110 cards:
Titan (18.0), 780Ti (20.2), Titan Black (20.5) and Titan Z (21.7).
Which in itself strongly suggests that these GPU's would be exceptional Maxwell candidates at 28nm...
Of course these are Very expensive cards and well out of most people's price bracket. However, the performance of two GTX750Ti's lays between a GTX780 and a Titan, but the two GTX750Ti's would cost a lot less to buy and a bit less to run.

PCIE x4 is unlikely to make a difference for a low-medium end card. You might see a bit of loss on a very high end card (GK110, especially a Titan Z) but if you wanted a card like that you would be using a high end motherboard.

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Thanks for your thorough response, skgiven! I hadn't thought of the dual 750Ti solution and God, is it tempting!!

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53% GTX 760
51% GTX 660

Since the middle of April my:

GTX 660 has done 92 WUs for an average of 11526 credits per hour
GTX 760 has done 116 WUs for an average of 13796 credits per hour.

I reckon the 760 beats the 660 by ~20% vs. your 2% (but then I may be comparing your apples with my pears…)

What do you think?

I think you may be right, but I was trying to compare reference cards.

The 53% and 51% are against a GTX Titan, which would make my estimation of the 760 ~4% faster than a 660 (and with a lot of variation); (53/51)*100%=104%.

Note that lots of Kepler cards have non-reference clocks, so expect line variations of over 10% (the GTX660 performance range could be from 50 to 56% of a Titan).

I may have been comparing non-reference 660's (back then the app didn't report the clocks). However, your 760 might be better than average, your 760 setup might be better, your 660 might be a real reference model or the 660 setup maybe isn't great/it's not boosting/cpu availability is poor...
Did the recent driver changes now allow greater boosting on the 760?
Maybe the app now works better for the 760, or the sample data I had just wasn't great. We would need to compare your 660 to other 660's to get an idea of it's performance. Ditto for the 760's.

Another noteworthy performance variation stems from different task types which utilize the GPU differently. This can result in different 'relative' performances across some cards.
Typically, there is a task type drift which is down to the different usages of memory interface width/Bandwidth (Frame Buffer in MSI Afterburner V 3.0.0) and the L2 cache factor.

Some examples of L2 cache:
GTX750Ti 2MB (GM107)

GTX780, GTX Titan 1536K (GK110)

GTX770, GTX680, GTX670 512K (GK104)

GTX660Ti 384K (GK104-300-KD-A2)
GTX660 384K (GK106-400-A1)

GTX650Ti 256K (GK107)

Performance comparison aside, a 760 is a 'slightly' newer version/model of the 660 (akin to the difference between a GTX460 and a GTX560).

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114%    GTX Titan Black
112%    GTX 780Ti
100%	GTX Titan
90%	GTX 780
77% 	GTX 770
74% 	GTX 680
59% 	GTX 670
58% 	GTX 690 (each GPU)
55% 	GTX 660Ti
53%	GTX 760 
51% 	GTX 660
47%     GTX 750Ti
43% 	GTX 650TiBoost
33%	GTX 650Ti

Hi Skgiven,

This analysis is nine months old. Any chance of an update, to include the GPUs marked in red below?

Thanks, Tom

211%    GTX Titan Z (both GPU's)
116% 	GTX 690 (both GPU's)
114%    GTX Titan Black
112%    GTX 780Ti
109%	GTX 980
100%	GTX Titan
93%	GTX 970
90%	GTX 780
77% 	GTX 770
74% 	GTX 680
59% 	GTX 670
55% 	GTX 660Ti
53%	GTX 760 
51% 	GTX 660
47%     GTX 750Ti
43% 	GTX 650TiBoost
37% 	GTX 750
33%	GTX 650Ti

This is a quick estimate but it should be accurate to within a few percent and serve as a reasonable guide on actual performance at GPUGrid.
The GTX900 series cards are the choicest for most GPUGrid crunchers due to their higher series (future proofed), compute capabilities, price and relatively lower power usages/performance. That said the GTX 780Ti, 750Ti and Titans, 690 and 660Ti still offer reasonable performance/Watt and power costs vary greatly world wide.

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Thanks! My pen is poised over my cheque book :)

If power efficiency is an issue go for a Maxwell based GPU.

With upcoming release of GTX960 (specs are all over the place and still unknown) If 10/11/12 SMM with 125watt power limit than the performance/wattage ratio will be top notch. GM200 could be two different boards- a full fat and cut down version (similar to Kelper's GK110 GTX 780.) This coming year for GPU cards will be a good one.

Skgiven:
If time permits for a new thread- would it be possible to create a table for per core power usage and per SMM/SMX wattage efficiency/Total power/runtime ratios? (similar to one in the Maxwell Now thread.)

Performance	GPU			Power	GPUGrid Performance/Watt
211%    	GTX Titan Z (both GPUs)	375W	141%
116% 		GTX 690 (both GPUs)	300W	97%
114%    	GTX Titan Black		250W	114%
112%    	GTX 780Ti		250W	112%
109%		GTX 980			165W	165%		
100%		GTX Titan		250W	100%
93%		GTX 970			145W	160%		
90%		GTX 780			250W	90%
77% 		GTX 770			230W	84%
74% 		GTX 680			195W	95%
59% 		GTX 670			170W	87%
55% 		GTX 660Ti		150W	92%
53%		GTX 760 		130W	102%
51% 		GTX 660			140W	91%
47%     	GTX 750Ti		60W	196%
43% 		GTX 650TiBoost		134W	80%
37% 		GTX 750			55W	168%
33%		GTX 650Ti		110W	75%

Note that these are estimates and that I’ve presumed Power to be the TDP as most cards boost to around that, for at least some tasks here.
I don’t have a full range or cards to test against every app version or OS so some of this is based on presumptions based on consistent range observations of other cards. I’ve never had a GTX750Ti, GTX750, 690, 780, 780Ti or any of the Titan range to compare, but I have read what others report. While I could have simply listed the GFLOPS/Watt for each card that would only be theoretical and ignores discussed bottlenecks (for here) such as the MCU load.

The GTX900 series cards can be tuned A LOT - either for maximum throughput or less power usage / coolness / performance per Watt:
For example, with a GTX970 at ~108% TDP (157W) I can run @1342MHz GPU and 3600MHz GDDR or at ~60% TDP (87W) I can run at ~1050MHz and 3000MHz GDDR, 1.006V (175W at the wall with an i7 crunching CPU work on 6 cores).
The former does more work, is ~9% faster than stock.
The latter is more energy efficient, uses 60% stock power but does ~ 16% less work than stock or ~25% less than with OC'ed settings.
At 60% power but ~84% performance the 970 would be 34% more efficient in terms of performance/Watt. On the above table that would be ~214% the performance/Watt efficiency of a Titan.

I expected the 750Ti and 750 Maxwell's also boost further/use more power than their reference specs suggest, but Beyond pointed out that although they do auto-boost they don't use any more power for here (60W). It's likely that they can also be underclocked for better performance/Watt, coolness or to use less power.

PM me with errors/ corrections.

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Thanks. It looks like a GTX 750Ti is currently the best replacement for my GT440; anything higher would require a new PSU and would probably trip the circuit breaker frequently.

This may change when more 900 series boards become available.

Thanks. It looks like a GTX 750Ti is currently the best replacement for my GT440; anything higher would require a new PSU and would probably trip the circuit breaker frequently.

This may change when more 900 series boards become available.

Most GTX750Ti's have a 6-pin power connector, so while they are rated as 60W TDP I expect many can use more power, if it's available. What's actually observed while crunching is key. This may throw/skew the performance/Watt rating substantially. Different card versions are built & tuned by manufacturers in different ways, some aim for efficiency, some for performance and some for cost.

While a GTX960 may well be on the horizon, it's likely to have a TDP of around 120 or 125W, with the GDDR amount and clocks determining a slightly higher or lower TDP. Such a card probably wouldn't fit your power requirements. I'm not sure when lesser cards will be introduced and there is little talk of them. The GTX750Ti was very successful, so NVidia might keep production going for a while longer.

If you look at NVidia's range of GPU's there are 2 Large TDP Power gaps. First between the 750Ti (60W) and the 192-bit 760 (130W) and from there to the 256-bit GTX760 (170W). The latter gap was recently filled by the GTX970 (145W) and 980 (165W), so it would be reasonable to presume the former gap (60W - 130W) will be filled by Maxwell's.
You have to go as far back as the 75W GDDR5 version of the GT 640 and the GTX650Ti (110W) to find anything between 60W and 130W. So it's a gap that I expect NVidia to fill out with Maxwell's. The question is when? My guess is that it's only a few months away, but it may or may not contain a revised 750Ti model.

If you do go for a GTX750Ti make sure you get a 2GB version and keep an eye on it's power usage; you can always force the GPU to run at a lower clock to use less power.

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Be aware that the GTX900 series cards can be tuned A LOT; either for maximum performance or performance/Watt. For example, with a GTX970 at ~108% TDP (157W) I can run @1342MHz GPU and 3500MHz GDDR or at ~60% TDP (87W) I can run at ~1050MHz and 3000MHz GDDR, 1.006V (175W at the wall with an i7 crunching CPU work). The former does more work, the latter is more energy efficient; ~27% faster or in theory ~30% more efficient (probably much more).

This information will help during the summer for dense systems with no Air Conditioner cooling. Lower temperatures = longevity. For Winter: the Maxwell can be tuned for Max performance while Summer season see's higher efficiency and lower temps with slightly longer work unit runtimes.

Thanks. It looks like a GTX 750Ti is currently the best replacement for my GT440; anything higher would require a new PSU and would probably trip the circuit breaker frequently.

Most GTX750Ti's have a 6-pin power connector, so while they are rated as 60W TDP I expect many can use more power, if it's available. What's actually observed while crunching is key. This may throw/skew the performance/Watt rating substantially. Different card versions are built & tuned by manufacturers in different ways, some aim for efficiency, some for performance and some for cost.

I'm running a lot of 750Ti cards (14 of them). The fastest stock 750Ti I know of is the PNY OC which has stock OC clocks of 1201/1281MHz (Afterburner reports 1346-1359MHz when running GPUGrid) and 3004/6008 memory:

http://www.pny.com/gtx_750_ti_2048mb_oc_pcie

Kill-a-watt reading is plus 60 watts after adding the GPU and running GPUGRID (94% usage). Some lower usage WUs draw less. Interesting that this model has no 6 pin connector, all power is from the PCIe bus even though it's probably the fastest 750Ti available. The EVGA OC Superclocked is almost as fast and also has no 6 pin connector. The fan on the EVGA is larger but both run at about the same temps. The 2 fan EVGA ACX runs cooler and does have the 6 pin. It's also just slightly slower than the PNY. I'm running 4+ each of the above 3 models and would recommend any of them without reservation. If installing in an environment where temps are a serious problem I'd recommend the EVGA ACX as its cooling is way more than normally needed. Also have 1 ASUS 750Ti OC - 2 fan model. It's considerably slower than any of my other cards, won't OC very much at all, runs at the same temp as the PNY and EVGA single fan models and has a very odd placement for the 6 pin connector. ASUS not recommended...

Here's a typical sd_err (SDOERR_BARNA5 at 94%) from a PNY housed in a tiny ITX case (running PCIe 2.0 x8. Notice temps are very good even with the ITX case and small PNY fan (fan speed 38% right now on a GERARD, probably a little higher for the SDOERR)):

<stderr_txt>
# GPU [GeForce GTX 750 Ti] Platform [Windows] Rev [3212] VERSION [65]
# SWAN Device 0 :
# Name : GeForce GTX 750 Ti
# ECC : Disabled
# Global mem : 2048MB
# Capability : 5.0
# PCI ID : 0000:01:00.0
# Device clock : 1280MHz
# Memory clock : 3004MHz
# Memory width : 128bit
# Driver version : r343_00 : 34465
# GPU 0 : 55C
# GPU 0 : 56C
# GPU 0 : 57C
# GPU 0 : 58C
# GPU 0 : 59C
# GPU 0 : 60C
# GPU 0 : 61C
# GPU 0 : 62C
# GPU 0 : 63C
# Time per step (avg over 3750000 steps): 11.679 ms
# Approximate elapsed time for entire WU: 43795.551 s
# PERFORMANCE: 87466 Natoms 11.679 ns/day 0.000 ms/step 0.000 us/step/atom

This information will help during the summer for dense systems with no Air Conditioner cooling. Lower temperatures = longevity. For Winter: the Maxwell can be tuned for Max performance while Summer season see's higher efficiency and lower temps with slightly longer work unit runtimes.

Hear, hear! Through the summer my main rig ran with a 770 and a 660 and I often had to shut off one of them because of critical PCIe heat.

In September I replaced the 660 with a 750ti. No more heat problems.

The GTX 960(ti) will feature [3] different dies. (8SMM/10SMM/12SMM) The 8SMM could be 70-100TDP with Ti variants being 100-130TDP.

[8SMM GM206 full or Cut GM206] [10SMM a full GM206 or cut GM204 same as GTX970m] [12SMM Cut GM204 same as GTX980m)
The 8SMM performance is 10~% a GK104/170TDP (1152CUDA) GTX 760. 10 SMM is 10-20~% of a full (1536CUDA) GK104/TDP195/230. The 12SMM is ~5% of a cut GK110 GTX780/TDP225 (2304CUDA)

Future Maxwell cards will excel at GPUGRID. Depending upon final release specs : 2/3/4 GM206 on a Motherboard will have similar power consumption compared to [1] GK104 or [2] GK106. Once GM206/cutGM204 are released it could put some Kelper boards to pasture concerning Watt/performance ratio.

-Subject to change-

GTX960-75TDP [8SMM/1024CUDA] 9.375 Watts per SMM @ 0.073 watt per core

GTX960(ti)-100TDP [10SMM/1280CUDA] 8.333 Watts per SMM @ 0.078 watt per core

GTX960(ti)-125TDP [12SMM/1536CUDA] 10.416 Watts per SMM @ 0.081 watt per core

Reference rated TDP Wattage per Fermi 32coreSM/ Kelper 192coreSMX/ Maxwell 128coreSMM

GTX580-244TDP [16SM/512cores] 15.25 watts per SM @ 0.47 watt per core

GTX760-170TDP [6SMX/1152cores] 28.33 watts per SMX @ 0.147 watt per core

GTX660ti-145TDP [7SMX/1344cores] 20.71 watts per SMX @ 0.107 watt per core

GTX660-140TDP [5SMX/960cores] 28 watts per SMX @ 0.145 watt per core

GTX680-195TDP [8SMX/1536cores] 24.37 watts per SMX @ 0.126 watt per core

GTX780-225TDP [12SMX/2304cores] 18.75 watts per SMX @ 0.097 watt per core

GTX780Ti-250TDP [15SMX/2880cores] 16.66 watts per SMX @ 0.086 watt per core

GTX750-55TDP [4SMM/512cores] 13.75 watts per SMM @ 0.107 watt per core

GTX750Ti-60TDP [5SMM/640cores] 12 watts per SMM @ 0.093 watt per core

GTX970-145TDP [13SMM/1664cores] 11.15 watts per SMM @ 0.087 watt per core

GTX980-170TDP [16SMM/2048cores] 10.62 watts per SMM @ 0.082 watt per core

Thanks. It looks like a GTX 750Ti is currently the best replacement for my GT440; anything higher would require a new PSU and would probably trip the circuit breaker frequently.

This may change when more 900 series boards become available.

Most GTX750Ti's have a 6-pin power connector, so while they are rated as 60W TDP I expect many can use more power, if it's available. What's actually observed while crunching is key. This may throw/skew the performance/Watt rating substantially. Different card versions are built & tuned by manufacturers in different ways, some aim for efficiency, some for performance and some for cost.

If you do go for a GTX750Ti make sure you get a 2GB version and keep an eye on it's power usage; you can always force the GPU to run at a lower clock to use less power.

Will a GTX750Ti (2GB) run without anything connected to the 6-pin power connector if I don't try to make it run faster than usual?

I bought one and tried to install it, but found that the computer doesn't have any power connectors that aren't already in use.

Do you know of any source of power cable splitters that would allow me to have a hard disk and the GTX750Ti share a power cable from the PSU? Probably also a few extenders for such power cables. Needs to be a source that will ship to the US.

Also, is there any comparison available for the crunch rates of a GTX750Ti and a GTX560? If the GTX750Ti has a high enough crunch rate, I'm thinking of moving nearly all my GPUGRID work to the GTX750Ti on one computer, and all my BOINC GPU work requiring double precision to the computer with the GTX560.

Not sure about installing the GPU without using a 6-pin connector, but in theory it should work. Until you started crunching it would not need much power and you could always power cap it using MSI Afterburner (or similar) before launching Boinc.

You would need 2 free molex sockets for this,
http://www.amazon.com/StarTech-com-6-Inch-Express-Adapter-LP4PCIEXADAP/dp/B0007RXDDM/ref=sr_1_1?s=electronics&ie=UTF8&qid=1421399317&sr=1-1&keywords=molex+to+6-pin

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