Zotac GeForce GT 640 DDR3 Review: Glacial Gaming & Heavenly HTPC
by Ryan Smith & Ganesh T S on June 20, 2012 12:00 PM ESTPower, Temperature, & Noise
As always, we wrap up our look at a new video card with a look at the physical performance attributes: power consumption, temperatures, and noise. NVIDIA is breaking new ground for desktop Kepler with their first sub-75W card, so it will be interesting to see just what the tradeoff is for such low power consumption.
| Zotac GeForce GT 640 DDR3 Voltages | |||
| GT 640 Idle | GT 640 Load | ||
| 0.95v | 1.00v | ||
NVIDIA doesn’t do a lot of voltage scaling with the GT 640. At idle it runs at 0.95v, and makes a short jump to 1.00v under full load. For a 28nm GPU 0.95v under idle is a bit higher than what we’ve seen in the past, which may explain the official 15W idle TDP.
Earlier we theorized that the GT 640 would have worse idle power characteristics than the GT 440, and this appears to be the case. The difference at the wall is all of 3W but it’s a solid indication that NVIDIA has at best not improved on their idle power consumption, if not made it a bit worse. The good news for them is that in spite of this slight rise in idle power consumption it’s still enough to tie the 7750 and beat older cards like the 6670 and GTS 450.
Long idle on the other hand sees the 7750 jump back into the lead, as NVIDIA doesn’t have anything resembling AMD’s ZeroCore power technology.
Of all of the sub-75W cards in our benchmark suite, the GT 640 ends up having the lowest load power consumption. Under both Metro and OCCT it’s equal to or better than the GT 440, GT 240, 6670, and 7750. AMD’s official PowerTune limit on the latter is 75W versus the GT 640’s 65W TDP, so this is not unexpected, but it’s always nice to have it confirmed in numbers. That said, for desktop usage I’m not sure 4-8W at the wall is all that big of a deal. So while NVIDIA’s power consumption is marginally lower than the 7750 they aren’t necessarily gaining anything tangible from it, particularly when you consider the loss in performance.
GPU temperatures look absolutely stunning here, and in fact it’s better than we would have expected. Zotac’s heatsink is not particularly large, and while these type of cards typically stay under 70C we would not have expected a single-slot heatsink to perform this well. If these kinds of temperatures can carry over into other designs there’s a very good chance we’re going to see some nice passively cooled cards in the near future. In the meantime buyers sheepish about high temperatures are going to find that Zotac’s GT 640 is an exceptional card.
Last but not least we have noise. Zotac’s card may be exceptionally cool, but that single slot cooler and small fan comes back to bite them when it comes to noise. That little fan simply doesn’t idle well, leading to the Zotac GT 640 being one of the loudest idling sub-75W card we’ve seen in quite some time. Zotac fares much better under load – where the 7750’s equally tiny and tinny fan leads to the 7750 ending up as the louder card by about 1dB – but really neither of these cards is particularly quiet for as little power as they consume. HTPC users who aren’t already looking at passively cooled cards are probably going to want to look elsewhere unless they absolutely need a single-slot card, as there’s a very clear tradeoff on size versus noise here.
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Joe H - Wednesday, June 20, 2012 - link
This is the type of review that other hardware sites can't even imagine, let alone write. Thanks for putting this and the other HTPC articles together. It's great to see a hardware review site taking HTPC enthusiasts and their needs seriously. Excellent review.n0b0dykn0ws - Wednesday, June 20, 2012 - link
Is there a chance of a follow up once a few driver updates have been released?I would love to see if the card gets even better after a few releases.
I have a Radeon 6570 right now, and I've found it to be palatable for HTPC purposes.
n0b0dykn0ws
Taft12 - Wednesday, June 20, 2012 - link
They haven't done it before, I don't know why they'd start now.Ryan Smith - Thursday, June 21, 2012 - link
What specifically are you looking for? Gaming performance or HTPC functionality? Gaming performance isn't likely to improve; even with the newer architecture it's not Kepler that's the limiting factor. HTPC functionality on the other hand can easily be improved with drivers.n0b0dykn0ws - Thursday, June 21, 2012 - link
HTPC only. For gaming I would get a 670.Sometimes drivers break HTPC performance/quality though. At least in the AMD world.
n0b0dykn0ws
Kevin G - Wednesday, June 20, 2012 - link
If they're going to release a DDR3 version, why not just offer a version with no onboard memory and two DIMM slots so that users can add there own? You can get a DDR3-2133 kit which would boost bandwidth limited scenarios by roughly 15%. While I don't see the need, such a card could be upgraded all the way to 16 GB of memory.MrSpadge - Thursday, June 21, 2012 - link
Sockets- are unconventional (I don't think nVidia likes this word)
- introduce a little cost (GPU manufacturer doesn't like it)
- make the board larger (GPU manufacturer doesn't like it)
- make the bus timing worse, so it's harder to clock them as high as directly soldered chips (wouldn't matter with DDR3, though)
- introduce another point of failure (GPU manufacturer doesn't like higher RAM rates)
- add cost to the overall product, as the end user wouldn't get as sweet a deal on RAM as the GPU manufacturer (this would eat into the GPU manufacturers profit margin)
Stuka87 - Wednesday, June 20, 2012 - link
Sounds like unless temps are really important to you, the 7750-800 is by far the better choice. It outperforms the GT640 (And by a wide margin in some cases) in what looks like, every single test.And they are priced the same, which makes the GT640 kind of worthless for its intended price point.
cjs150 - Wednesday, June 20, 2012 - link
Great review.It is too noisy, and the HDMI socket is an epic design fail. As a card for an HTPC what were Zotac thinking of? This is so badly wrong.
Now onto frame rates. Nvidia, AMD and Intel really are total and utter idiots or they have decided that we the customers are total and utter idiots. There is simply no excuse for all IGPs and video cards not to be able to lock on to the correct frame rate with absolute precision. It is not as though the frame rate specs for film have changed recently. I cannot decide whether it is sloppiness, arrogance or they simply do not give a rats a##e for the customer experience.
Stuka87 - Wednesday, June 20, 2012 - link
God forbid there be a technical reason for it....