GeForce GT 640 is NVIDIA's first low-end product based on their new Kepler architecture. It introduces the 28 nanometer production process to this segment, and also brings many other architectural improvements. Unfortunately NVIDIA's boost clock algorithm is missing, which helped GTX 600 series gain some extra performance when competing against AMD's offerings. Our benchmarks conclusively show that GT 640 is not a graphics card for gamers. While it can handle some basic gaming at lower resolutions and low details, it has a hard time competing even with cards at a similar price point. ZOTAC's choice of 2 GB of memory instead of 1 GB makes very little sense from the perspective of an enthusiast user. It makes perfect sense from a business standpoint though, because people still buy cards that have big numbers written on the package.
Unlike many other GT 640 cards, ZOTAC's board comes in a single slot form factor, which makes it attractive for the media PC crowd. Instead of going for a full-size HDMI output, ZOTAC chose to use a mini-HDMI output, adding a second dual-link DVI connector to the card. While other reviewers reported issues finding an adapter for the mini-HDMI output, I had no such problems, it would still be nice if ZOTAC had included a mini-HDMI to HDMI adapter in the box.
Thanks to the NVIDIA's energy efficient GPU design, power consumption and heat output are very limited. Actually, GT 640 is one of the most power-efficient solutions for multi-monitor and Blu-ray playback, because NVIDIA's driver goes to the lowest possible power state with recent drivers, something that's missing from AMD cards. On the other hand AMD cards feature ZeroCore power, which will help reduce power consumption for media PCs that are always on, to download content for example.
While ZOTAC's cooler does its job well, keeping the card cool, it does so with way too much noise. Our noise testing puts the card on the same noise levels as graphics cards that are three times faster! It's not NVIDIA's fault though, their design is power efficient. It seems that ZOTAC forgot to fine-tune the fan settings to the capabilities of their cooler, or they decided that low noise is not for low-end graphics card users.
Pricing of the GT 640 is awful. Currently the ZOTAC GT 640 is available online for $110, which gets you a HD 6790, that's 50% faster. If you want to spend less, go for the HD 6670, which offers similar performance but costs only $65. If you are only interested in media PC capabilities, then there are cheaper alternatives out there that offer similar features, also in single slot form factor, some of them even passively cooled.