Anyone using GTX 660 TI SLI?

SLI/CFX Is wasting money, 2 Cards doesn't translate to 200% performance and so on.

I tried it before and I was not happy. That's why I said stick to single cards as much as possible.

I dont believe I stated he should with 4+ monitors, run using just 2 660tis. Just asked why he wants to sli or a 680.

yeah, that does work . . . I've just seen 680s down to the same price as 660 ti's at ncix. . .

680's are on sale more.

Only 2 cards have microstuttering, I searched up that if you add a third card microstuttering just magically disappears.

Got an ASUS mobo, I doubt it :)

Many people with enthusiast computers with high-powered SLI video nowadays are having a meltdown of one or two pins on their 24-pin ATX mainboard power connector (actually one of those pins is on the 4-pin add-on plug, or one could call it the 20+4 pin plug), particularly pins 10 and 11 (+12V). This has only begun happening since high-end video cards have started drawing a lot of power - like those that draw >100W. Said video cards have extra power connectors on them, which must be used to supplement the video card power, but apparently they are not supplying enough extra power in all these cases. It doesn't help that the sockets that carry this current have to be made very cheaply, meaning the manufacturers cannot afford very good quality control for them. And I have not seen any that are gold-plated for better conductivity/lower resistance. EVGA has issued a "powerboost" PCIe cable, that plugs in to a 4-pin molex power connector from your PSU, and into any available PCIe slot, to help mitigate this melting 24-pin ATX plug problem.

This affects all motherboards designed for SLI/Xfire except those with the extra 4-pin molex plug(s) added for PCIe auxiliary power.

Reasoning (logic behind my hypothesis)

The root of this problem lies in the way electricity moves, and the use of plugs not designed to withstand such electrical current. The video cards draw 12V power primarily, and this power is available through both the PCIe bus and the extra card power plugs (6-8 pin). But electricity will follow the path of least resistance, thus meaning if a bad connection exists on the 6-8 pin plugs it will flow more from the PCIe bus, which in turn comes from the 24 pin ATX power plug - +12V pins 10 and 11. So bad connections could cause this problem, and I am not referring to the 24 pin plug exclusively. But all this theory assumes that the voltages supplied to each plug are exactly equal!

Present day consumer computer power supply units (PSUs) are made quite cheaply due to market competition. As you may know, the cheap units are generally much less reliable than the more expensive ones (there are exceptions). And most PSUs that are rated more than 650W use multiple "rails." These are basically separate circuits of the same general voltage. The single-rail units are generally significantly more expensive, and thus most consumers buy the multi-rail PSUs. I could get into a discussion here of the advantages/disadvantages of a single-rail PSU, but that's another subject. Each rail contains its own current limiters and regulators. These components are not perfectly matched, nor professionally adjusted to an exact voltage, thus each rail can vary a bit in voltage output. This is fine in many cases, but in the case that the voltage is higher on the primary rail, this means more of the amperage supplied to the video cards is likely to come through the 24 pin connector! What's more, the voltage supplied is likely to drop slightly as current draw increases. Thus when the video cards begin to gulp power the voltage on their rails drops slightly, meaning more amperage is likely to be drawn through the 24 pin ATX connector at that point. Also, any loose sockets on the video cards plugs will cause additional resistance on that circuit, also causing more current draw from the 24 pin ATX connector instead.

Therefore, if a power supply is used that has a bit higher voltage on the main rail as opposed to the video rails, it is more likely to melt the 24 pin ATX connector. This means you can measure the likelihood of your system being highly susceptible to this occurrence. I suggest you measure the voltage on pins 10 and 11, and then on pins 1, 2, and 3 of the PCIe power plug. Pins 1, 2, and 3 should be almost exactly the same voltage. Compare these to pins 10 & 11 voltage, exactly. If 10 and 11 are higher, you have a high-risk of contracting the melted 24-pin ATX plug problem (theoretically). Variations of just 0.02V should be ignored, such small voltage differences could be caused by voltage changes in the time between moving your probes, and probably also beyond the accuracy of your instrument. In my opinion it would take more like 0.05 or 0.1V differences to be significant. Voltage measurements can be made using just about any black wire on the 24-pin plug for ground (a.k.a. 0V), always use the same one for every measurement you report. Measurements may differ during different load conditions, such as CPU load vs SRAM load vs graphics load; and component temperatures may change the readings as well.

tl;dr version

This affects all motherboards designed for SLI/Xfire except those with the extra 4-pin molex plug(s) added for PCIe auxiliary power, if a power supply is used that has a bit higher voltage on the main rail as opposed to the video rails, it is more likely to melt the 24 pin ATX connector. If you have a single-rail PSU you should be less likely to have the melted 24-pin ATX plug problem if this hypothesis proves true, since your voltage measurements at all +12V points should theoretically be exactly the same except very slightly lower where a lot of power is flowing. The extension of this theory is if your 24-pin ATX plug pins 10 & 11 are at least 0.1V under your PCIe plug voltages, you should never have the melted 24-pin plug problem.