Our today’s menu features XFX Geforce GTX 260 640M, an overclocked GTX 260 card based on the same GT200 core like the rest of the GTX 200 series. 640M in the name stands for 640MHz and XFX made sure to point that out. The company overclocked the core by 64MHz (reference speed is 576MHz) and boosted the stream processors from 1242MHz to 1363MHz.
Geforce GTX 260 card uses the same dual slot cooler we’ve already seen on GTX 280 (the stronger card in GTX 200 series), so telling the cards apart just from looks is not an easy task. We’ve already tested XFX GTX 280 670M here, and the only visible difference on the two following photos is the 8-pin connector; GTX260 uses two 6-pin connectors, whereas GTX 280 uses one 6-pin and one 8-pin connector. Both coolers run silently when the graphics card is idle, but they get quite audible under a workload. XFX painted their GT200 based cards nicely, and the first one is GTX 260 640M. Underneath it you’ll find a photo of XFX GTX 280 670M running at 670MHz.
In case you’re not familiar with it, Geforce GTX 260 is a weaker version of the current single GPU champ known as GT200. Full versions of GT200 are found on Geforce GTX 280, and we’ve already mentioned XFX GTX 280 670M as one of the fastest ones around.
GT200 is a powerful graphics processor with 1.4 billion transistors and 240 stream processors. The last G92 generation (that brought Geforce 9800 GTX) had 128 stream processors, which further paints the picture of just how powerful GTX 280 is. The weaker version, GTX 260, has a bit less - 192 stream processors, which is a result of a one disabled ROP channel and two shader clusters, each packing 24 stream processors. By crippling the card, the production costs get cheaper, so GTX 260 is a wise choice for many that can’t afford GTX 280.
One thing we have to mention is the goodwill of XFX and the respect for their North American customers. Apparently, some faithful enthusiasts paid an arm and a leg for GT200 cards right after they were announced, only to be shocked by recent sudden price drops. Fortunately for their customers, XFX has a program where they’ll rebate $120 USD per card.
You are eligible for this rebate if you bought your XFX GTX200 card between the 16th of June and 11th of July 2008, and the amount of cash you’ll get back depends on the model, the date, as well as the price paid for the card, where $120 is the most XFX will rebate. You can find out more about this program here.
XFX GTX 640M has a frame buffer of 896MB GDDR memory with 448bit memory interface. Thanks to the overclocked memory, bandwidth is now up from reference 111.8GB/s to 128.8GB/s. For these additional 17GB/s of bandwidth, XFX had to increase memory speeds from reference 999MHz to 1150MHz (2300MHz effectively). At the same time, they’ve outdone their HD 4870 competition that has a bandwidth of 115.2GB/s. However, GTX 280 is still undefeated with a bandwidth of 141GB/s (XFX’s overclocked card, XFX GTX 280 670M, packs 160GB/s).
Less memory bandwidth on GTX 260 is a result of crippling the chip. In case you don’t know, each of the 8 ROP partitions on GTX 280 is connected to a 64-bit memory controller. From there, it’s easy to conclude that this card has a 512-bit memory interface, whereas GTX 260 with 7 ROP partitions totals to a 448-bit memory interface – and therefore less bandwidth.
Although it’s not as fast as GTX 280, GTX 260 is quite an appealing GPU. It packs 192 stream processors, 28 ROPs, 64 texture units, 448bit memory interface and 896MB of GDDR3.
GTX 260 packs 896MB of GDDR3 evenly spaced across both sides of the card. Each side features 7 memory chips, each with 64MB, whereas GTX 280 has 8 chips per side. The following photo shows one vacant spot where a memory chip was supposed to go (vertical column on the right, first one next to the PCIe connector).
If one GTX 260 card doesn’t strike your chord then don’t worry, as GTX 260 supports TriSLI. For that purpose, two SLI connectors are provided, but we can leave them hidden until the need arises.
The card is powered through two 6-pin power connectors, unlike GTX 280 which needs a 6-pin and an 8-pin connector. Maximum consumption is 182W, but it’s unlikely that this will be the case, as this card supports HybridPower technology. This technology (coupled with an appropriate chipset) enables the GPU to power down, thus leaving non-demanding tasks to be rendered by the motherboard’s integrated graphics. GT200 can also power down certain unused parts of the chip as well as dynamically regulate frequencies and voltages.
You can use GTX 260 for 3D “Graphics Processing Mod” or for “Parallel Compute Mode,” meaning processing data on the GPU using CUDA (Compute Unified Device Architecture). This is where Nvidia’s marketing really shines and they’re selling GT200 series with a slogan “Beyond Gaming.”
For those of us that still use the GPU exclusively for gaming, XFX went that extra mile and included Assassin’s Creed with their card. The packaging is nicely assembled and painted, so walking by without noticing it on the shelf will be difficult.