Weak link in my system?

I finally finished upgrading my HTPC to Windows XP MCE 2005 running an ATI HDTV Wonder tuner card, so I record in HD. For the most part, it works great, although I have bit more driver tuning and configuring to do.

I also have a Hauppauge PVR 250 as a second tuner card for the non-HD channels, and so I can dual record two shows at the same time.

When I record a single HDTV show at a time, it works fine. Smooth playback, no skipping, etc. However, when I record an HDTV show, and a non-HD show at the same time, the HDTV recording gets sluggish, skipping frames, etc., while the non-HD show records fine.

I'm running at 1080i resolutions through DVI to my Sony 50" HDTV. I'm using nvidia's DVD software decoder, and the latest nvidia drivers for MCE.

So it seems my system doesn't have enough horsepower to record 2 shows at the same time. I'm trying to figure out where the weak link is before I just start blindly upgrading things that may not need to be upgraded. So is it my CPU? memory? video card?

Here are the specs of my HTPC machine:

Athlon XP 2200+
512MB Corsair DDR 266
Dual Maxtor 60GB 7200 drives in RAID 0 for operating system
300GB 7200 RPM Seagate Barracuda ATA 133 (for TV recordings)
MSI Geforce FX5200
Turtle Beach Montego DDS 5.1 SPDIF
ATI HDTV Wonder
Hauppauge PVR-250

So is my best bet to upgrade the memory to 1GB?
Or upgrade my processor to an XP2700+ (or whatever the fastest Socket A chip is, as I don't want to replace my MB)
Or upgrade my video card?

Thanks in advance!

Use performance monitor to see if the paging file is being used excessively and by which process. Computer Management, Performance Logs and Alerts, Counter Logs. Create a new log and add the counters you need. I suggest starting with memory - pages/sec , processor - processor time and physical disk - average disk queue length.

My guess is more memory, but if the average disk queue length is much greater than zero for any length of time, disk I/O is the bottleneck. Ideally the average disk queue length should be zero - nothing waiting for disk I/O. each I/O is in process (serviced) immediately.

I checked the CPU utilization during playback of a 1080i HD recording, and it was 85-90% in full screen mode, occassionally spiking to 100%, which is also when I would notice some pausing in the video and skipped frames. I'm running nVidia's PureVideo decoder, but unfortunately my FX5200 doesn't support PureVideo's HD playback acceleration on the GPU.

My main system has a 6800 GT 256MB card, so I'm thinking of throwing that into my HTPC system and see if it helps with the HD playback performance and lowers the CPU utilization. Unfortunately, the 6800 doesn't support WMV9 acceleration, which is what MCE records HD content in.

However, the 6600 does support WMV9 acceleration, and if my 6800 helps at all, I think I will buy a 6600 card. My next question is, does it make any sense to get the 256MB model versus the 128MB model? Does the extra video memory help with HD encoding and decoding, playback, etc. and for general HTPC purposes? I won't be running any video games on this machine - it will only be a HTPC and media server. I know video games can take advantage of the extra video memory with large texture maps, etc., but I'm not sure if it is of any benefit with video playback.

Thanks!

I think you are simply doing too much. Wihtout specific hardware the HD recording is going to kill the CPU. Adding another SD recording on top of it is out of the question - especially for that processor. Hell, the 2200+ is barely capable of playing HD without hardware assistance. In your case, it is better because of the ATI card, but it is still not ideal.

You would really want a dual core processor to do dual recordings.

Just a follow up that may be useful for people in a similar situation.

I temporarily replaced the FX5200 video card with a Geforce 6800GT from my main computer. Wow what a difference!! Now it plays completely smooth HD video, while recording two shows in the background, streaming video to my xBox through extender, you name it. No matter what I threw at the system, it handled the load fine with no slowdown in HD playback. HD recordings were smoother too.

Checking CPU utilization, during normal HD playback, it is only 30-40% consistently, in full screen 1080 resolution, and running 5.1 DTS encoding through my Turtle Beach Montego DDL. This is compared to 85%-100% before with the FX5200. I then tried recording an HD show in the background, and a non-HD show at the same time while watching an HD recording. Utilization went up to only 60-75%, and never hit 100%, playback smooth. CPU utilization during HD recording only (not watching at same time) was only 10-15%!

A true test was the Super Bowl. It played back perfect HD quality the whole 3.5 hours without missing a beat.

So, I went and ordered a new 128MB 6600 card (so I can put the 6800GT back in my main PC), and will retire the FX5200.

Now all I have to do is solve my cooling and fan noise problems (probably going to go water cooled), and get a better HD antenna. Then I'll be a really happy camper with my HTPC.

Nice to hear. What do you save your hd file as? Hdv? Mpeg4? How much space did the super bowl take. Sounds nice. I have a hard drive recorder for regular tv, because of the noise of my pc. But now I have a silent small shuttle.