The Importance of Support Infrastructure

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The Importance of Support Infrastructure

Postposted on Fri Jun 06, 2014 9:32 pm

I'm going to make this post a bit long, just to make sure all details are here and people can learn as much as they might hope from the post. There is historical development of a problem, through its ultimate solution.

Recently, I purchased a new Sapphire R9 290 Tri-X to replace my old Sapphire HD 7950. This was to support my Eyefinity setup (3 ASUS VE248Qs).

Now, as many of you may remember, prior to the advent of the R# 2## series cards, to use Eyefinity, you had to have at least one monitor fed by a DP out from the card. The affected my monitor purchasing strategy. The VE248Q supports 1x DP, 1x HDMI, and 1x D-Sub as its input choices.

The HD 7950 I had came with 2x mini-DP, 1x HDMI, and 1x DVI inputs. The original connections were setup as follows (unless noted, all cables are male on each end):
    - Monitor 1 (left): Mini-DP out from 7950 to DP in on VE248Q; Startech.com 3m miniDP-to-DP cable
    - Monitor 2 (main/center): Mini-DP out from 7950 to DP in on VE248Q; Startech.com 3m miniDP-to-DP cable
    - Monitor 3 (right): HDMI out from 7950 to HDMI in on VE248Q; RCA 3m HDMI-to-HDMI cable

This setup worked pretty well. It was actually interesting to note that the HDMI-driven monitor was the slowest to respond out of sleep. Additionally, in this setup, the monitors would not always hold position when changing Eyefinity group setups. I believe this is related to the slower polling of the HDMI monitor (similar to it coming out of sleep). That was a minor annoyance (I don't always play my games in 5760 x 1080 mode), but I lived with it.

With the R# 2## series cards, however, Eyefinity no longer required DP. This meant (as was immediately seen on reference cards) that we would be less likely to see multiple DP ports on a single card. At that same time, one is fairly unlikely to see multiple HDMI ports. I knew I was going to have a problem soon. While a single DP out is known to be able to support 3 Full HD monitors, this requires a DP hub or daisy chaining monitors. DP hubs have long been promised, but were not at that time easily available (Club3D had one available in Europe, but that was about it). My monitors couldn't daisy chain; it was a feature I'd looked for, but that was cost prohibitive for me.

This meant I had to plot my move to an R9 290 carefully. I was mildly hopeful that a custom card would have multiple DP outs, but hope is a bad strategy. For better or worse, as I was waiting for the custom card of my dreams, the prices of R9 290s skyrocketed; that bought me more time. Fortunately, EVGA released a DisplayPort Hub; I'm pretty sure I was one of the first dozen people to have one delivered, since I went so far as to order from EVGA (they actually ran a nice sale for early adopters). That opened up a world of future choices in R9 290s once the prices came down.

In the meantime, it was time to buy some new cables and try the new setup. It looked like this:
    - DP Hub: Mini-DP out from 7950 to DP in on DP Hub; Startech.com 3m miniDP-to-DP cable
    - Monitor 1 (left): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable
    - Monitor 2 (main/center): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable
    - Monitor 3 (right): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable

This setup was fairly solid. Occasionally, coming out of sleep, one of the monitors would not come back. This was solved by pressing the "scan" button the hub, to re-poll the monitors. This did not register as a significant warning sign to me, since EVGA had felt they needed the button on their device. It seemed reasonable to assume this was just a fact of DP hubs. The issue was also intermittent enough that I didn't really notice how often it occurred. It may actually have been resolved by a driver update, but I'm not certain. The one big thing I noticed, however, was that the issue I'd noticed with the HDMI monitor's slow response was gone and that Eyefinity setups stuck more consistently. Overall, this was net goodness.

Finally, prices stabilized on cards and I got my R9 290. Setup seemed simple. I would simply have to use the 1m DP-to-DP that came with the EVGA DP Hub and balance against required cable lengths:
    - DP Hub: DP out from R9 290 to DP in on DP Hub; Startech.com 2m DP-to-DP cable
    - Monitor 1 (left): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable
    - Monitor 2 (main/center): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable
    - Monitor 3 (right): DP out from Hub to DP in on VE248Q; EVGA 1m DP-to-DP cable

This is where things got really weird. I'd be sitting around using my computer, and all the monitors would go black. Activity didn't really make any difference. I didn't even have to do anything to create this issue. I could be sitting around watching Netflix and the monitors would go black, but the sound would continue. The Netflix case was actually good for ensuring the computer was still working. I could move my mouse to the Netflix window, click on it, then use the space bar to pause or resume, I could control volume with the keyboard, and occasionally I could even start something else with sound just to prove the computer itself was still just fine. It was just the monitors. Usually, unplugging the DP in from the hub and plugging it back in would be sufficient to bring back the monitors, though it might take doing this multiple times. In one case (and only one), pressing the "scan" button brought the monitors back to life. So, I knew I had an issue. This happened multiple times each day, typically at a rate of more than once per hour while using the system.

While trying to figure out what was going on, I noticed an interesting and new feature in Catalyst Control Center (I don't know when it showed up, but it was new to me). You could determine the bandwidth usage along different DP paths. Everything should have been fine, but it was interesting to note that the output from the R9 290 was using 72% of its bandwidth. It got me thinking. Then I found this article at the DP consortium's website. Basically, there are some bad DP cables out there that just seem to cause problems. Doing more research on those lines, I found there were a few people who were actually getting BSODs due to bad DP cables (I don't know the logic there, but it seems the cards try to protect the system from something and just shut down the computer). I also found there were no firmware updates for the hub or the monitors.

While StarTech.com does have some properly rated cables, none of the ones I was using were listed as such. Honestly, though, those worried me less than the one from EVGA. I didn't do extensive testing, though. I knew that the StarTech.com cables were capable of carrying a single signal from the hub to the monitors. The EVGA cable was a mystery at any point. So, I found an accredited cable (in this case, a 3m Belkin), purchased it and adjusted the setup. It now looked like this:
Finally, prices stabilized on cards and I got my R9 290. Setup seemed simple. I would simply have to use the 1m DP-to-DP that came with the EVGA DP Hub and balance against required cable lengths:
    - DP Hub: DP out from R9 290 to DP in on DP Hub; Belkin 3m DP-to-DP cable
    - Monitor 1 (left): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable
    - Monitor 2 (main/center): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable
    - Monitor 3 (right): DP out from Hub to DP in on VE248Q; Startech.com 2m DP-to-DP cable

The system is now steady as a rock, with no noticeable problems. I've been running for about a week now with no issues.

So, just goes to show: that support infrastructure that we all take for granted can be quite important. Don't neglect it in your troubleshooting.
FightingScallion
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