T-simulation OUTLINE Inputs to the T-simulation: chips, boards, crate mechanics and fan T-simulation performed into two steps: On large scale: simple AM chip model, but full crate sim, AMB_V2 - Results On small, deteailed scale: AM06 package detailed model inserted, AMB_V3, but simplified crate simulation- Results Future cooling tests plan and conclusions

Detailed T-simulation (IMEC) for the new AMBSLP  to know T on silicon! Optimize chip package and boards dissipation Estimate the temperature in the chip silicon knowing T just outside the package ALL details must be taken into account from package design to crate, PS, fan design Heat Sink Die size Die underfill Substrate RDL Tall DC-DC converters in the middle AMB with four LAMBs model LAMB model Crate & fan model What we have understood is that in the crate the pcb is hot and the air is very cold. This happens because the resistors do not exchange heat with the air. So these boards full of resistors are good to stress the power but not so good to emulate the behavior of the final Associative Memory Boards. Now we are repeating the test with 3 AMBboards full of old Amchips, with mechanical and termal characteristics more similar to the final ones. We will use also a different fans module, the Wiener Hyper Blower, to avoid the hot spots and maximixe the air flux. Understanding the importance of the package and PCB design to optimize the heat dissipation, we asked also to IMEC a temperature simulations at the chip, board and global system level.

NOVEMBER 2014 SIMULATION Inputs - AMB_V2 Large Artix FPGAs DC-DC 1,2 V

Air flow in the crate simulation Not efficiently cooled slots Bad slots

Next to Worse AM pos Worse AM pos

10 m/s Simulated As uniform 4 m/s Simulate the Worse case (blue) with Max=3,2 & 4 m/s

AMB_V2 Full crate sim Simple AM06 Lower air flux

94.5o Inside the red box: max T = 94.5o Inside the black box: max T = 79o max in the Bad slots with red arrows (on the left of the box) On the right part of the black box (good slots) T= 61o, 67o, 72o, 73o, 70o, 69o, 75o and 64o These are temperatures in good slots where the DC-DC is far.

NEW T-SIMULATION March 2015 Improving the AMBSLP layout Detailed model for AM package (see next slides) AMB_V2 AMB_V3 New inputs to the simulation TOT= 247W

AM chip + PCB piece With air flow (4 m/s) Results 39,75 Results

55 C

99,4 Worse slot 99 degree on Die is acceptable

88 Near to worse-slot 88 degree on Die is acceptable

3 slots are even worse than worse simulated case CPU position + 2 SSB Worse case shown Other 3 slots have similar behaviour as worse cases shown by T-sim 2 SSB + 1AM Max T ~99 ±5 degrees, acceptable However it is a conservative estimate: Average flux larger than the simulated one The simulation does not allow the x component of air velocity Lowering the fan with respect the crate  more uniform flux

Conclusions The AM06 package has very low resistance: die T ~ package-PCB T. Conservative simulation predicts TMax AM06 die ~99o  ok Lowering the fan or using a diffusor we can have a more uniform flux of air, uniform temperature, and lower TMax We will do new cooling tests to see if the T differences between slots detected by the T-sim correspond to the observed differences We will measure the temperatures for different setups of the free space available in the rack.