DPC latency lesson

Logan and Wendell I think the subject of DPC latency would be a good hardware topic to be addressed as some stage. Its quite interesting, when I first had issues many years ago - socket 775 and through to x58 etc I learnt a lot and it has since been helpful in diagnosing mystery faults.

Lots of people are unaware what it is, what happens when dpc latency is high. What causes it, etc.

Ive addressed and helped in threads in the past here on this forum and several others as there are certain characteristics of issues that flag a dpc latency issue, but I though it would be worthwhile addressing to a larger audience.

High dpc latency is a right p.i.t.a, it can make a beast of a system behave like a hairy goat. Mainly with audio.

Very few review sites even cover the issue when doing reviews of hardware. Anandtech are the only consistant site that covers it.

Yeah, just an idea feel free to ignore I wont be offended.

Peace.

yeah, its indeed a good thing.

Its a real pain in the ass. im dealing with high dpl since day one that i had my AMD setup. it seems that AM3+ boards with realtek lan suffer from this issue allot.

As far as i have nailed it down, its some kind of a leaking issue, making systems unstable, this issue seems to be present in windows vista / 7 and server 2008. In Windows 7 that i use the audio services crashing allot, and lan lagging. But Microsoft ignore every single complain about it. They refuse to fix it.

Allot of people suffer from this, especialy with amd setups, but also the older intel platform seem to suffer from it aswell. Its a bit hard to nail down, where exactly the things go wrong. is it a windows fault? is it a driver related issue? is it just a problem with the mobo´s its all hard to say. But i have the feeling, that in windows 8.1 the issues seems to be less present. or atleast, the system doesnt seem to get unstable that fast anymore. But still there is some kind of lagg present on lan.

If there are people who suffering from high dpl issues with newer intel setups, i would realy wanne know that.

The thing that i can tell you from now, is that im sooo totaly done with it, that i have decided to upgrade my system to intel.

Till now i did not seen any complains from people that are on newer intel setups, Z87 Z97 X97 X99. on Windows 7. So im a bit in a dubio about it.

I think its a combination of things - poor motherboard design - eg X58 UD3R rev1.0's had terrible latency. Of which I successfully claimed a rma on one. Rev. 2 was somewhat of an improvement.

As well as shitty windows driver prioritization. They have known about this for close to 10 years now, no excuse.

Windows 8+ uses different kernal timers hence the >1ms readings minimum in latencymon or sycon's dpc checker.

Yes am3 boards are inherently bad, but so to are some modern z97 boards. Some vendors released bios updates that alleviated a few bugs at least. That was when the first few boards were coming onto the scene.

Those modern Z97 board, will probably be the lower end ones with realtek lan, and older ALC-892 audio chips i suppose?

But i also remeber a thread that i have readed somewhere, about people with killernik E2200 lans had some leaking issues with Windows 7. idk if thats fixed yet by qualcom, if im right Msi and Asrock Z77 / Z87 boards in particular.

This is in fact one of the most interesting topics in the "PC Master Race" crappile for the moment, I totally agree on that.

It's one of the most absurd failures of the Microsoft software console, together with the broken filesystems and lack of security features.

Now DPC and latency is a serious issue, and part of the problem is the latency that most "gaming" mobos add to the equation.

I've said this before, but every test ever conducted in terms of gaming performance, shows that cheaper "business" boards are quite a bit faster than expensive "gamer" or "enthusiast" boards. Sometimes, the difference between a standard H-chipset board and a top end Z-chipset board (especially Asus seems problematic) is as much as 30 %. The least thing a gamer should do, is buy anything marketed towards gamers, the best thing to do is to get the model that is sold the most, the real mass market stuff, that has a big impact on the market, and that has the manufacturer's and Microsoft's reputation at stake.

However, Microsoft just seems not to have a solution for the DPC caused gaming performance drop in Windows, especially in Windows 8, as demonstrated by their own answers site: https://answers.microsoft.com/en-us/windows/forum/windows8_1-system/windows-81-dpc-latency-issue/2c949374-b52d-4bdf-b908-dc6a9836d85f

Ah right so the issue still exists in windows 8?

I think that the high dpl issues, is one of the reasons why Asus probably decided to use intel lan on most of theire Z97 ms boards. And i think this is also one of the reasons why they probably have skipped on killernik gaming lan on theire ROG boards.

it seems that killernik uses more cpu sources because of a leaking issue or something like that. i cant remeber exactly, but i have readed a topic about it. I personaly avoid boards with "gaming lan" but prefer a decent intel lan.

The only thing i can tell you, i did dpl latency tests allot, and i experianced, wenn i playing music or video offline, with disabled lan chip, there is nothing wrong, no high dp spikes nothing, but as soon as i enable the lan chip, the dp starts to spike like crazy and after a few minutes i get an error from latency checker. it says its caused by the realtek lan chip.

Never knew about this.  I wonder what Barnacles would say about this.

I also don't really understand it, but perhaps a few more articles...

A few articles later, I understand a bit more.

This mainly results from shifty drivers, huh?

http://www.sweetwater.com/sweetcare/articles/solving-dpc-latency-issues/

http://forums.guru3d.com/showthread.php?t=377960

Does some one has any experiance with the Asus maximus VII Hero, wenn it comes to DPC latency issues?

Im allready digging arround the net, but i cannot realy find any info about it. Anandtech bench tested a couple of Z97 board, but not the Hero if im right.

Since im on my point to purchase a new board, i would like to know user experiances.