Post Cards from the Edge - AMD 780G, NVIDIA 790i, Gigabyte 680i

AMD 780G Motherboards

It has been an agonizingly slow process dissecting seven boards and trying to devise a set of benchmarks that satisfy the home theater, casual gaming, and home office crowds all at once. We think our roundup will come close but there are sure to be a few bumps in the road. We await your comments on the upcoming video analysis and roundup articles over the coming days.

However, we almost did not finish our testing (we actually still have some Phenom benchmarks to complete) as we lost four of our seven boards during final benchmark sessions this past week. It very easily could have been seven out of seven, but we stopped the killing spree after verifying why our boards seemed content to go to digital heaven without Kevorkian assistance. We could stop here and say wait for the article, but that would be sensationalist journalism, right?

Our normal course of testing has us installing a wide variety of processors in each board, regardless of the target market. We do this to ensure compatibility, and at times (like now) we wish this was not the case. This week, we tested the 780G boards with the LE1600, 4400+ X2, 4850e X2, 6400+ X2, Phenom 9600BE, Phenom 9900, and now the 9850BE.

We discovered quickly that running the 9900/9850BE or 6400+ X2 on these products resulted in the loss of the board, in a matter of a few seconds to a few minutes. Granted, it will probably be rare that a user will purchase a 9850BE to run on this platform, but in case you were considering that course of action, we highly suggest you do not. Let’s get this out of the way quickly; it is not a 780G chipset problem.  In fact, it is not strictly a board problem either, but rather a design issue.

This design issue can just as easily occur on NVIDIA or Intel chipset boards, so while we are talking about the 780G product line, just be aware that it can happen on any board with any chipset. In fact, our last GeForce 8200 has already experienced a painful demise. The design issue comes down to the manufacturer trying to balance performance requirements and costs when providing a product in this market sector. The budget sector is very price sensitive, and for the most part users will typically use a lower-end processor.

The vast majority of the 780G boards have a three-phase or four-phase PWM circuitry design. These designs are completely acceptable for the 45W, 65W, 89W, and 95W TDP rated processors; however, drop in a 125W TDP processor such as the Phenom 9850e or 6400+ X2 and you are asking for trouble. Trouble is exactly we found, as each board we tested eventually succumbed to the greater power requirements of these 125W TDP processors.

The four-phase motherboards held out longer and seemed to run fine at stock speeds for a short period. Trying to overclock these boards even slightly resulted in almost immediate board failure. The three-phase boards did not fare as well since we blew MOSFETS on power-up, or they failed after a short OCCT load. We have returned the failed boards for analysis. However, we are comfortable with our statements after spending the past two days on the phone with the board manufacturers and AMD.

Now for the kicker. Although we were testing with a Phenom processor, that does not mean the manufacturer had qualified the board with this particular CPU. So while those front page ads and marketing information list all the processor families that will theoretically run on a board, users need to read the fine print or search for the suppliers' QVL/CPU support lists to ensure the desired processor has been qualified. We also plan to provide this information in the review process.

We searched each vendor’s website to find out if we were “running” the board out of spec with the 9850BE/9900 processors. What we found was very interesting, and we are having spirited discussions with the motherboard companies and AMD at this time.