4 Replies Latest reply on Feb 16, 2010 7:54 AM by Bobins

    Warning: RST and DPC Latency


      Long story short: I had been using Rapid Storage Technology 9.5.4 for quite a while, and then (unwisely) reconfigured a number of things on my Windows 7 64-bit system at the same time, including upgrading to RST  A few days later, I then noticed stuttering in iTunes, and eventually got to the point of using the tool "dpclat" to measure my DPC Latency: it declared it unacceptable due to bursts.  After a number of failed experiments, I reinstalled RST 9.5.4, and the stuttering is gone.  iTunes is solid, and "dpclat" reports no high latencies.


      Obligatory irrelevant system info: Intel Core i7 Extreme 965, Gigabyte GA-EX58-UD4P, 12 GB Corsair, four Seagate 7200.11 1.5 TB drives, two eVGA GeForce GTX 260, Creative Sound Blaster X-Fi Titanium.

        • 1. Re: Warning: RST and DPC Latency

          You're not the only one with this problem. I don't know what the difference between the 9.5.4 and 9.5.6 drivers is but whatever Intel have done it's introduced terrible DPC latency problems in 9.5.6 resulting in bad video & audio stutter. Back to 9.5.4 the problem goes away.


          Taken me hours of diagnostics, fiddling & reboots to pin it down to the driver. (using dpclat & xperf)


          Similar system to yours: Intel Core i7 , Gigabyte GA-EX58-UD5, 3 GB Corsair, four Western Digital Raptor 36Gb drives (Raid 5), ATI 1900 PCI-e video, Creative Sound Blaster X-Fi (software version). Windows 7 (64bit) Ultimate


          Message was edited by: Bobins

          • 2. Re: Warning: RST and DPC Latency

            Thanks Bobins for confirming my observation, at least for your config.  From the amount of attention I was being given in the main RST 9.5.6 thread, I was beginning to think I was imagining the whole thing :-)

            • 3. Re: Warning: RST and DPC Latency

              I don't know if it's just me, and gigabyte boards, but I always get DPC latency issues if I'm using the default Vista/7 power plan..


              EP35-DS4 (BIOS F6)  - Win7 x64

              and EP45-UD3 (BIOS F9) - running Vista x64


              I don't know if it's cosmetic or what.. but the minute I change Vista/7 to "High performance", suddently DPC latency disappears.

              • 4. Re: Warning: RST and DPC Latency

                Thanks Ozz.


                I currntly run my system in "High Performance" mode all the time and I've tried disabling all the bios "power saving" options one-by-one.


                The only thing that made a difference was going back from 9.5.6 to the 9.4.6 drivers.


                I suspect that something Intel is doing to improve the SSD compatibility of the software is moving it away from supporting some combinations of motherboard and mechanical drives. (a SATA 1 support isue perhaps?)