Some questions about the Geforce GT640


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mherr170
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Message 1463811 - Posted: 13 Jan 2014, 4:34:20 UTC
Last modified: 13 Jan 2014, 4:52:11 UTC

Hello Everyone,

I decided to look over the top rated GPU models for the Seti project, and then look them up on newegg to see how expensive they would be.

Number 25 on the list is GeForce GT 640, and when I looked that model up on newegg I was shocked to see the price! This model is 2GB and is only 99$. That initially sounds like a really great deal.

Does anyone have an opinion as to whether this would be a good upgrade?

My current number 1 cruncher has the following - NVIDIA GeForce 8800 GTS 512 (512MB) -and- AMD AMD Radeon HD 7700 series (Cape Verde) (1024MB).

Would dual 2GB Geforce GT640s be the momumental upgrade to my rig that it seems it would be on the surface? To overhaul my cruncher and give it a new breathe of life for only 200$ (for both cards) sounds too good to be true...

Aside from faster crunching, electricity efficiency is also on my mind in regards to this upgrade. Would these potentially new cards be more worth the electricity to power them over what I currently have?

Any advice or thoughts on this subject is much appreciated :)

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Message 1463817 - Posted: 13 Jan 2014, 4:51:11 UTC

Great question. I was thinking of upgrading my Nvidia GTS 250 to a GTX 640. Im wondering what the PSU requirements are. They never seem to tell you that on Newegg.
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Message 1463820 - Posted: 13 Jan 2014, 4:56:58 UTC
Last modified: 13 Jan 2014, 4:58:24 UTC

Sometimes they do mention it on newegg, but certainly on this card's title page. In the Customer Q&A section, some folks start mentioning some wattage, but nothing definite seems to amount from it.

I am sort of crossing my fingers that my current PSU would be able to handle it, seeing as it already can handle more than 1 card. This is probably a bad thing to assume, but PSUs are still something I am getting used to worrying about.

Just to clarify James, this model is a GT 640. You mention a GTX 640. Are they something different?

Edit: Heading to bed, will catch up in the morning!

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Message 1463825 - Posted: 13 Jan 2014, 5:07:48 UTC

I think your right. The GT 640. Sorry it gets confusing trying to keep up with the nomenclatures.
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Message 1463831 - Posted: 13 Jan 2014, 5:32:25 UTC

It is crappy gpu. That is why they put 2 GB of memory on it, to make it look more attractive. The extra gig of memory is not going to do anything for you.
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Message 1463834 - Posted: 13 Jan 2014, 5:35:57 UTC

Biggest problem is that card only has DDR3 memory, while the better cards all run DDR5.

I would recommend at least a GTX650Ti or better.

Minimum PSU for the 640 is 350 watts, while the 650Ti needs a 400 watt PSU and 1 6-pin connector.
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Message 1463836 - Posted: 13 Jan 2014, 5:42:13 UTC - in response to Message 1463811.
Last modified: 13 Jan 2014, 5:57:19 UTC

I'm currently running 2 Galaxy GT 640s on an HP xw9400 box. Both have just 1GB of memory. I tend to scrounge for stuff, so I bought the first one (used) on Amazon last May for $44.12, delivered. It was first installed in my HP dc7700 for a while, then briefly replaced an 8600 GT in my IBM ThinkCentre, before being added as a 3rd card in the xw9400. I bought a second used one on eBay in November for the grand total of $45.00, delivered! That was then added as a 4th card on the xw9400.

Both GT 640s are connected to riser cables plugged into x16(x8) slots, while the 2 primary cards, a GTX 650 and GTX 660 are plugged directly into the x16(x16) slots on the board. The GT 640s actually reside outside the box, see my Message 1448807.

I run stock apps on that machine and adding the 2nd GT 640 seemed to add about 3-3.5K to my RAC over the first 6 weeks or so (before the recent server problems put a dent in the RACs of the most productive machines). The 1GB memory size of my cards seems to be more than adequate to run 2 tasks per GPU, as I do. I suspect anything more would be pretty much just excess capacity.

As far as electricity use goes, the 2nd GT 640 added about 40-50w to my total power use on that rig, somewhat below the rated TDP for the card.

EDIT: I should probably mention that this machine only runs 138 hrs/wk, so the 3-3.5K contribution of the 2nd GT 640 would probably be about 20% higher if it was running the full 24/7.

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Message 1463838 - Posted: 13 Jan 2014, 5:50:15 UTC - in response to Message 1463834.

I would recommend at least a GTX650Ti or better.

I was thinking the same thing.
For the price & the power usage & the work done per hour it'd be about the sweet spot at the moment.
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Message 1463842 - Posted: 13 Jan 2014, 6:09:51 UTC

Thanks I guess I will just keep my GTS 250 in my store bought rig.
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Message 1463846 - Posted: 13 Jan 2014, 6:18:54 UTC - in response to Message 1463842.

Thanks I guess I will just keep my GTS 250 in my store bought rig.

According to one list that I have, that old GTS 250 actually draws more power than a GTX 660, and more than twice as much as a GT 640. Depending on your electric rates, you might want to do some cost/benefit calculations! :-)

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Message 1463847 - Posted: 13 Jan 2014, 6:20:39 UTC - in response to Message 1463842.

Thanks I guess I will just keep my GTS 250 in my store bought rig.

The GTX 650 TI actually uses less power than the GTS 250. Even the 650Ti Boost uses less power, but has higher memory & core clock speeds than the 650Ti.
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Message 1463852 - Posted: 13 Jan 2014, 7:08:00 UTC

A 8800 GTS's rated maximum draw is 145W, a GTS 250 is 150W and while crunching these would be pretty much on those limits.

OTOH my GTX 660's are rated at 140W yet while crunching they only draw on 90% of that (126W) while being miles in front on work done.

Just something else to think about.

Cheers.

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Message 1463883 - Posted: 13 Jan 2014, 10:03:43 UTC

Look at http://www.geforce.com/hardware for various graphic cards specs.
The GTX650 1GB looks a better choice vs. the GT640: compared with the GDDR5 version the GTX650 has about the double of memory bandwidth with +30% power consumption, compared with the GT640 GDD3, the GTX650 is more power efficient.
You can find a GTX650 on the $120.00 range, I've installed a PALIT brand with satisfaction.
Dont't look for a 2GB one, it's a waste for crunching as the GTX650 is a relatively low number CUDA cores card (the same as GT640).
You need to have two 6-pins power plug adapters for having them installed in your machine and a minimum 600W PSU for the twin.
Look also at http://setiathome.berkeley.edu/show_host_detail.php?hostid=7144422 for expected performance in a single card arrangement.
It's one of my two owned rigs I run. Mind I'm running almost exclusively AP6.
Difference with the GTX650TI can be evaluated by comparison with the other rig I'm running at http://setiathome.berkeley.edu/results.php?hostid=6391954 .
Cheers.
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Message 1463929 - Posted: 13 Jan 2014, 14:05:19 UTC
Last modified: 13 Jan 2014, 14:34:55 UTC

Thank you everyone for weighing in on this subject. It seems pretty clear that I should be looking towards a GeForce GTX 650 or GeForce GTX 650ti. Both of them are not much more expensive than the GT640.

Unfortunately the GeForce GTX 650ti is out of stock on newegg at the moment, so I may lean towards the GeForce GTX 650 if they don't restock.

All that seems to need to be known now is if my PSU can handle dualing these cards. I do have two 6 pin power connectors currently, so at least that part should be okay.

Thanks again everyone!

Edit: I want to thank Jeff Buck for giving his quite detailed description about the cards I asked about. Thanks Jeff.

Also, Thanks to Leo for his detailed description of the card most people say I should be considering. Leo, you are of course doing Astropulse pretty much exclusively on your cards. Would anyone have an estimate on how much RAC a MB only dual GTX 650 or GTX 650ti would produce? My two current cards seem to produce about 5k RAC.

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Message 1463943 - Posted: 13 Jan 2014, 14:55:58 UTC - in response to Message 1463929.

These are some Thermal and Power Specs for the carda:

GT640DDR3 98°C MaxTemp 65W Max Graphics Card Power 384CUDA cores
GT640DDR5 95°C MaxTemp 48W Max Graphics Card Power 384CUDA cores
GTX650 98°C MaxTemp 64W Max Graphics Card Power 384CUDA cores
GT650IT 105°C MaxTemp 110W Max Graphics Card Power 768CUDA cores
GT650ITBOOST 97°C MaxTemp 134W Max Graphics Card Power 768CUDA cores

I'm running 3 WU at time on the DUALCORE GTX650 rig and 4 WU on the quadcore GTX650TI one.
If You don't know how to run multiple instances on single videocard, refer to optimized client thread in this forum for.

Take care.
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Message 1463947 - Posted: 13 Jan 2014, 15:13:36 UTC - in response to Message 1463929.


Unfortunately the GeForce GTX 650ti is out of stock on newegg at the moment, so I may lean towards the GeForce GTX 650 if they don't restock.

Newegg has several different models of the GTX650Ti in stock currently.

Here is an Asus model with twin fans.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121686
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Message 1463959 - Posted: 13 Jan 2014, 16:11:00 UTC - in response to Message 1463929.
Last modified: 13 Jan 2014, 16:18:07 UTC

...Would anyone have an estimate on how much RAC a MB only dual GTX 650 or GTX 650ti would produce? My two current cards seem to produce about 5k RAC.

You would probably receive about the same RAC you are at present with one 650TI. I have about the same two cards as you and with running only 1 CPU task and APs on the 7750, my RAC is close to the single 650TI which is running more CPU AP tasks.
Number of processors: 2
Coprocessors: NVIDIA GeForce GTS 250 (1024MB) driver: 332.21 OpenCL: 1.00, AMD AMD Radeon HD 7700 series (Capeverde) (1024MB) driver: 1.4.1848 OpenCL: 1.02
Average credit: 19,411.03
After running some Un-Blanked APs for a while, the RAC will move to around 20k.

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Message 1464004 - Posted: 13 Jan 2014, 17:51:56 UTC

Mherr,

I am running two 650 TI's in one of my machines.

http://setiathome.berkeley.edu/hosts_user.php?userid=8826827

After doing what was recomended in this thread

http://setiathome.berkeley.edu/forum_thread.php?id=73726

my RAC has been climbing VERY nicely. It hasn't leveled off yet but I am very
pleased.

mherr170
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Message 1464010 - Posted: 13 Jan 2014, 18:26:15 UTC - in response to Message 1464004.

Thanks everyone for your continued input!

Mherr,

I am running two 650 TI's in one of my machines.

http://setiathome.berkeley.edu/hosts_user.php?userid=8826827

After doing what was recomended in this thread

http://setiathome.berkeley.edu/forum_thread.php?id=73726

my RAC has been climbing VERY nicely. It hasn't leveled off yet but I am very
pleased.


This may be obvious, but in general do you run your rig with the two 650ti's 24/7?

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Message 1464050 - Posted: 13 Jan 2014, 20:09:58 UTC - in response to Message 1463836.

I'm currently running 2 Galaxy GT 640s on an HP xw9400 box. Both have just 1GB of memory. I tend to scrounge for stuff, so I bought the first one (used) on Amazon last May for $44.12, delivered. It was first installed in my HP dc7700 for a while, then briefly replaced an 8600 GT in my IBM ThinkCentre, before being added as a 3rd card in the xw9400. I bought a second used one on eBay in November for the grand total of $45.00, delivered! That was then added as a 4th card on the xw9400.

Both GT 640s are connected to riser cables plugged into x16(x8) slots, while the 2 primary cards, a GTX 650 and GTX 660 are plugged directly into the x16(x16) slots on the board. The GT 640s actually reside outside the box, see my Message 1448807.

I run stock apps on that machine and adding the 2nd GT 640 seemed to add about 3-3.5K to my RAC over the first 6 weeks or so (before the recent server problems put a dent in the RACs of the most productive machines). The 1GB memory size of my cards seems to be more than adequate to run 2 tasks per GPU, as I do. I suspect anything more would be pretty much just excess capacity.

As far as electricity use goes, the 2nd GT 640 added about 40-50w to my total power use on that rig, somewhat below the rated TDP for the card.

EDIT: I should probably mention that this machine only runs 138 hrs/wk, so the 3-3.5K contribution of the 2nd GT 640 would probably be about 20% higher if it was running the full 24/7.

To add to what Jeff said. He bought two used gt 640. When I looked at newegg the other day, they had refurbished gtx 460 and gtx 560 for less than new gt 640. So. If you don't mind used, then you have much much much better cards available to you for less money than crappy gt 640.
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