We don't normally comment much on heat with graphics cards, but the GeForce 9800 GX2 is an exception because the heat this card produces caused us some headaches along the way. We encountered a number of heat-related crashes, hard locks and instabilities with our Asus Striker II Formula motherboard.The thing was, these problems were limited to only when the GeForce 9800 GX2 was installed in the board. With two GeForce 8800 GTS 512MB cards in SLI, there were no problems and the story was the same with the GeForce 8800 Ultra as well – we're 100 percent certain that the problems we encountered were entirely related to the installation of the GeForce 9800 GX2.We witnessed temperatures in excess of 90 degrees Celsius on both the nForce 200 chip and the south bridge on the Asus motherboard – this triggered the company's overheat protection feature that automatically shuts down the motherboard to prevent long term damage.Throughout all of our testing, we closely monitored GPU temperatures after we first encountered stability problems and they never exceeded 85 degrees Celsius, which is pretty good for a graphics card—especially one with two GPUs so closely packed together. In fact, Nvidia says the point where the GPU starts to throttle itself down is when the core reaches a temperature of 105°C for reference purposes, so there's still quite a bit of headroom.
A fan placed directly above the south bridge prevented these heat related problems from cropping up again. And after a lot of time spent stress testing GeForce 9800 GX2 cards in other motherboards (such as XFX's nForce 780i SLI and nForce 790i SLI boards, as well as the Gigabyte GA-X38-DS5), we have come to the conclusion that system instability may occur on nForce 700-series motherboards with the nForce 200 chip located in between the top two PCI-Express x16 slots. In that location, the chip is right underneath the GeForce 9800 GX2 and, with the card being covered in what is essentially a big heatspreader, a heat pocket is created underneath the card. The problem as I see it is that when Nvidia set the design guidelines for partners to adhere to when designing nForce 780i SLI motherboards, Nvidia gave engineers the freedom to place the nForce 200 chip wherever they pleased – there were no limitations imposed. During my conversations with Nvidia's nForce 780i SLI engineers last October, I asked on several occasions whether the nForce 200 chip had a significant TDP because I had spoken to several motherboard engineers that had complained about the increased TDP requirements for the chipset.Every time I asked the question, I was told that the TDP increase was insignificant. That may be the case with the Nvidia-designed board used by some partners, but it's definitely not the case here with a GeForce 9800 GX2 installed in the Asus Striker II Formula. The problem for motherboard engineers was that they probably didn't know a great deal (if anything) about the GeForce 9800 GX2 and the amount of heat it produces. And because Nvidia imposed no strict limitations on the placement of nForce 200, the problem has come out into the open.It's sad that we have to put a downer on this card's performance, but we have to make you aware of what you may encounter if you're using one of the more popular nForce 780i SLI motherboards on the market. This isn't XFX's fault, or even really Asus's fault either – it's just a bit of a mess that wouldn't have come about if Nvidia had imposed design limitations on the placement of the nF200 chip.
The main thing to compare here today is the performance of the 9800GX2 against the HD 3870 X2 from AMD. We’ve also thrown in the 8800GT, as the specifications on a single core of a 9800GX2 is only slightly above that of an 8800GT, this should mean that if a game doesn’t take advantage of SLI then the performance should only be just above the single 8800GT.
