IRQ sharing with the Matrox P750 has never been a problem though. Today I'm using BIOS 1015 for the A8V because of the crazy USB over current error message during POST which won't go away if it appears. Manual allocation of IRQ’s is not possible with this board.
/*/ A8V Deluxe Rev. 2 BIOS 1017
/*/ Athlon64 X2 4800 no OC
/*/ 4x1GB OCZ4001024ELDCPE 200MHz CL2.5-3-2-5
/*/ 2x Samsung Spinpoint SP251 250GB PATA1 & PATA2
/*/ 1x WD Raptor 740GD SATA1
/*/ 1x Maxtor Diamondline III 300GB 7B300S0 SATA2
/*/ Matrox P750 with xp2k_110_01_114_se_u Latency 32 IRQ 16 shared with FW1394
/*/ UAD-1 V4.1 PCI_1 Latency 64 IRQ 16 shared with FW1394
/*/ UAD-1 V4.1 PCI_2 Latency 64 IRQ 17 shared with Marvell GB Lan
/*/ UAD-1 V4.1 PCI_3 Latency 64 IRQ 18 shared with Promise IDE/SATA/RAID deactivated
/*/ RME HDSP Digiface 2.943 PCI_4 Latency 255 IRQ 19 not shared
/*/ UAD-1 V4.1 PCI_5 Latency 64 IRQ 16 shared with FW1394
/*/ WinXP Pro SP2 latest patches
/*/ Sonar 5.0.1 PE
This setup works up to 97% UAD CPU load without any pops and crackles i.e. 28 1176LN 7 PPI’s per UAD-1 @44.1kHz 256/512/1024 latency.
Looping within Sonar requires a UAD-1 CPU load below 90% @44.1kHz 1024 latency to work reliable otherwise host CPU spikes up to 100% with dropout.
The switches /3GB and Userva=2900 in boot.ini seem to make no obvious difference but I’m not 100% sure how to find out.
HKEY_LOCAL_MACHINE\\SOFTWARE\\Universal Audio\\Powered Plugins\\UAD HypTopo\\DMATurbo=1. Setting this one to 0 causes crackles and CPU spikes during looping.
During installation of WinXP SP2 it was required to press F5 when pressing F6 is possible to choose the right HAL (halmacpi.dll) for ACPI Multiprocessor PC. Otherwise WinXP has not recognised the dual core CPU with its two cores. Only one core showed up in device manager after installation! (See MS KB299340)
Using latest AMD processor drivers 1.2.2 from AMD seems to be mandatory for correct recognition and function of CPU independent from the fact if cool and quiet is used or not. During DAW use CPU power scheme should be set to continuous operation to avoid problems from lowering voltage and frequency.
Most important thing is MS Hotfix 896256 for multiple processors! Without this patch WinXP SP2 will not use core 0 and core 1 in a load balanced way. Core 1 got the higher CPU load without having the patch installed and dropouts occurred. (See MS KB896256)