ASUS PhysX P1: PCB Design and Cooling System

AGEIA PhysX physics accelerator is a relatively small card equipped with a small cooler. At first glance it looks very similar to a graphics card, because you do not notice that there are no D-Sub/DVD connectors right away.

Looks like the PCB design follows closely one of AGEIA’s engineering samples, because there are a few technological connectors close to the fastening bracket that haven’t been laid out. The voltage regulator circuitry of AGEIA PhysX is quite complex and includes a lot of capacitors, even though the card hardly consumes more than 20-25W of power. The heart of this circuitry is two Intersil ISL6522CBZ PWM-controllers that control the work of AC-DC converters. Since PCI bus cannot provide enough power, the card is equipped with a standard four-pin Molex connector.

Since PhysX processor uses PCI 3.0 interface with 3.3V signals, it is tied up to this connector via three Texas Instruments TW222A chips. These elements consist of 23 NMOS transistors each and serve to limit the input-output signal level. This way, they protect the PhysX chip against damage if the card is installed into a 5V PCI slot.

Having removed the cooler we got access to the PPU chip and could read its marking.

The chip is marked as AG10011-P revision A1 and is manufactured on the 40^th week of last year. In other words in the end of September – beginning of October 2005 AGEIA already had second revision of working PhysX chips at their disposal (the first revision was A0). Looks like it took them so long to get the cards into the market because they were working on the software all this time.

The die of the PhysX chip manufactured with 0.13micron technology is quite big and makes around 190sq.mm. As we have already said before, we do not know what frequency it works at.

The card is equipped with four GDDR3 Samsung K4J52324QC-BC20 chips in 136-pin FPGA packages. Despite the fact that these are 512Mbit chips, the total amount of onboard memory available for the PPU is 128MB. Maybe half of the memory banks are simply not used at all. The nominal frequency for the BD20 chips is 500 (1000) MHz, however the memory of PhysX P1 solution works at 366 (733) MHz. keeping in mind the low heat dissipation of the new 136-pin packages and lower working frequency they do not need any extra cooling.

PPU core is equipped with a cooler, which you should have already read about in our articles called NVIDIA Multi-GPU SLI Technology: New Approach to Old Ideas and ASUS N6600 GT/TD Graphics Card Review. The only difference between the PhysX P1 cooler from the other two is the color: in our case it is copper-colored. The cooler location is not the optimal one, because the PPU die appears right under the fan motor, which is a practically dead zone. For the most optimal cooling effect it should have been placed beneath the ribbed heatsink cooler by the air stream from the fan. However, since PhysX works at not very high clock speed, it shouldn’t be a big problem and the cooler should perform its functions well enough.