Attached is the final product. Perhaps it will help someone else with a non-standard CPU on PCB. I wasn't really wanting to get into thermal tapes in this thread as there was another thread for that, which I had started thinking that I would use thermal tape for this application, but decided against it. Thermal tape for heatsinks, particularly for DRx2-66 and SXL2-50+
I connected the 5V fan wire to J1 on the interposer and left the masking tape in place on the clips since it is barely visible. These chips will clock well to 80 MHz, but I'm not daring enough to test for 100 MHz. The system it is going in can only handle up to 70 MHz on this chip - at higher frequencies, the CPU won't clock double for some reason. If anyone has any input on that anomaly, please refer to this thread: How to get 486 SXL2-66 to clock-double w/AMI Mark V Baby Screamer motherboard
This chip is destined for my AMI Mark V Baby Screamer 386 with ULSI DX2-66 FPU, a SCSI2SD HDD, SCSI2SD - Comparison of SCSI SD, CF, and HDD performance , and native PS/2 mouse adaption, Re: Native PS/2 mouse implementation for 386/486 boards using the keyboard controller . Unfortunately, the CPU sits right under the HDD mounting bay and I estimate that the distance between the top of the fan and the mouting bay is 0.6 cm. I hope this is enough distance for the fan to operate properly. The fan runs at 7500 rpm and pushes 3.7 CFM.
The two washers under the fan are used as spacers because the centre of the heatsink is every so slightly taller than the surrounding fins, roughly 0.25 mm taller.
I was also wondering if having an inductive load (the fan) connected directly to J1 is the best approach. Would this introduce some distortion to Vcc? But on second thought, the CPU is being powered from a 3.3 V regulator on the interposer which should help in this regard.
Is anyone interested in creating the PCB for the PGA-168 version of the SXL2-66 to run on PGA-132? If so, Custom interposer module for TI486SXL2-66 PGA168 to PGA132 - HELP! . This way, just about everyone who wants to run an SXL2 on a 386 at 66 or 80 MHz can do so.
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