New Mac Pro 4k 60hz MST = messed up wifi?

Question

Level 1

0 points

New Mac Pro 4k 60hz MST = messed up wifi?

I have a brand new Mac Pro and the Sharp PN-K321 4k monitor.

Everything works perfectly fine when I have the monitor in SST mode (that can only do 4k at 30hz). If I switch the monitor to MST (multi stream transport) mode to do 60hz at 4k then my basically goes out!

It took me a while to track this down... but there is no question about it. SST wifi is perfect. MST wifi is dropping packets like crazy (if it connects at all). I suspect that there's some sort of interference in the signally of MST mode and the wifi antenna in the Mac Pro.

I know that not many people have this configuration yet... but has anyone seen anything similar? I'm wondering if there might be a short somewhere and maybe the machine needs to go back. This combo has been acting weirdly since I got it... it was working with one of my miniDP->DP cables... then it stopped. It works with another miniDP->DP cable but has this wifi issue...

Very strange...

Macbook Pro, Mac OS X (10.5.5), and Mac Pro

Posted on May 12, 2014 6:16 PM

Reply

Answer 1

May 12, 2014 7:20 PM in response to Friedmud

Hold down theOption key while you click on the WiFi Icon on the menuBar. You should get a display like this:

What do you get for PHY Mode?

Channel?

RSSI (Signal Strength)?

Transmit Rate?

Also, how many OTHER networks do you see competing with yours?

Reply

Answer 2

Friedmud Author

Level 1

0 points

May 12, 2014 8:32 PM in response to Grant Bennet-Alder

How about this... I started in MST mode... and at that halfway point there I switched to SST on the monitor. Notice how the noise fell off and the SNR skyrocketed? I think that's pretty decent proof!

Reply

Answer 3

Friedmud Author

Level 1

0 points

May 12, 2014 8:33 PM in response to Friedmud

To answer your other question I only see one other Wifi network currently...

Reply

Answer 4

May 12, 2014 8:49 PM in response to Friedmud

If you have a Router that only uses the 2.4GHz band, it is already known to be subject to:

interference from microwave ovens, cordless telephones and Bluetooth devices.

--according to wikipedia.

You spent a lot of money on that nice new Mac Pro. Now it is time to get an up-to-date dual-band Router so that you can get away from the baby monitors (and MST displays, it seems) and get some decent throughput.

Dual Band adds six to twelve additional channels in the 5GHz band, and wider ones, so that can get you significant additional throughput.

Reply

Answer 5

Friedmud Author

Level 1

0 points

May 12, 2014 8:55 PM in response to Friedmud

It appears to be related to the placement of my MiniDP->DP cable.

I kept that graph open and tried rearranging the cable and I watched the Noise line. By wrapping that cable around the Mac Pro (which is sitting right next to the monitor) I can get the noise to go up to -83 in MST mode! There are varioous other arrangements that are bad as well... the best so far is just to "crumple" it in a mess... that basically makes the noise fall off the bottom of the chart.

In SST mode there is nothing I can do with the cable to even make the Noise show up on the chart (meaning it's all below -90). Even wrapping the cable around the Mac Pro a couple of times does nothing.

This leads me to believe that MST signaling is putting out a crap ton more EM... and to deal with it I'm going to need a more shielded cable. The cables I'm using are pretty cheap Monoprice cables that are pretty thin - so I'm sure they're not helping things.

Unfortunately my company (in their infinite wisdom) decided to order this monitor from a third-party instead of from Apple ("But we saved $250 on that $3500 monitor!"... sigh). SO I don't have the official cable that would have come with the monitor... which I'm sure would have been higher quality (all I got with the monitor is DP->DP...)

Can anyone recommend a good miniDP->DP cable? There don't appear to many around...

Reply

Answer 6

Friedmud Author

Level 1

0 points

May 12, 2014 8:59 PM in response to Grant Bennet-Alder

Thanks Grant - I've been thinking of doing just that (getting a new router)... but this router has been rock solid for me for 6 years so I've hesitated to switch.

I'm getting ready for a move soon (to Boston in fact... which I see is where you're from!) and I expect there will be quite a bit more Wifi interferance there so I'm probably going to have my hand forced anyway....)

Thanks for chiming in!

Reply

Answer 7

May 12, 2014 9:14 PM in response to Friedmud

I got the new Apple Dual-band 802.11ac Router as a refurb (I didn't know they were ever offered as refurbs) and saved some money. It seems to be working great.

I don't have any 802.11ac devices, but having Dual band has increased my WiFi speeds (when used) about five-fold.

Reply

Answer 8

Aug 7, 2015 2:36 PM in response to Friedmud

Cannot believe this but - it's true.

Late 2013 MacBook Pro with mini Display -> Display port cable running a brand new 4k monitor and everything was great until I got around to cleaning up my desk and re-arranging the wires to look neater. Tucked the mini display cable under the dock I was using to hold the computer and ... ? ... wifi cut out? Unplugged the computer from the cable, back on again?!

Saw this post and did nothing more than to move the cable 12" away from the computer and out from under the dock and the computer is working great again. Thank-you Freidmund for the investigation... saved me some hassle for sure!

Reply