How many PCIe Extensions is TOO MANY??

Linus Tech Tips ·Linus Tech Tips ·2018-05-06 · 1,366 words · ~6 min read
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0:00 okay so when we were building our wall pewter wall computer well pewter get it
0:04 anyway one of the challenges was having the graphics card on the opposite side
0:10 of the frame versus the motherboard i mean this thing was so far away that
0:16 there wasn't a single pci express riser
0:19 cable on the market that was able to reach
0:23 so the solution use more pci express risers we actually
0:28 ended up with a one meter thermaltake
0:31 premium extender chained to a 30 centimeter one and we
0:37 pulled it off with no performance degradation whatsoever the system worked
0:41 perfectly fine which got us thinking
0:46 just how far can you go
0:50 before things go haywire
0:53 stick around while we uh snake our way
0:58 to the conclusion
1:09 browse privately and securely with tunnelbear the simplevpn app start your
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1:18 okay so to kick off the experiment we rigged up our standard GPU bench machine
1:23 so it's a known good machine our pci express signal integrity should be about
1:28 as good as it can get then we needed an extra piece so we also hooked up a
1:34 separate power supply for our gtx 650 ti
1:38 graphics card this is so that we don't actually run into power cable length
1:43 limitations if the experiment goes completely off the hook
1:48 also having an excuse to call out to ivan like he's far away is a
1:53 is a bonus so uh hit the power switch chekov
1:57 so i did catch that can you repeat
2:00 hit the i'm right here oh engage in auxiliary
2:04 power now thank you roger don't have ignition
2:10 i'll turn on the system so to kick things off
2:16 we're going to be using a single one meter extension
2:20 plus an additional 30 centimeter extension that's a total of
2:25 130 centimeters this is the same as what
2:29 we did for the wall pewter one more lower there you go
2:33 stress test go so it's running perfectly
2:38 as expected which means
2:41 it's time to kick it up a notch baby let's take it to
2:45 160 centimeters would you look at that still no dropped
2:50 frames let's add more look at this
2:54 it's ridiculous yeah
2:58 down down down right there yep
3:02 no 1.9 meters
3:07 our pci express extensions are almost the height of darth vader
3:14 okay so we're adding another 40 centimeters this time
3:18 you can tell those thermaltake guys have a lot of confidence if they send us this
3:22 much PCIe riser i am excited this was the best pci
3:28 express riser technology we had around here so
3:31 these aren't even shielded these you legitimately can't go very far
3:35 with like i tried uh daisy chaining even two of these together and i had trouble
3:40 with it so oh
3:44 do we have failure okay let's try disconnect and reconnect
3:48 just to make sure that we're being fair to it
3:51 come on baby is the 650 ti PCIe gen 3 yet
3:59 okay so maybe our load just isn't demanding
4:04 enough maybe we need to bring out the big guns
4:09 a titan xp okay so let's shut it down and let's try again so
4:14 look at this okay so do you remember back when they
4:18 launched this thing there was a bunch of press around the missing PCIe pins look check
4:24 this out so these are power and then
4:27 this is all data and NVIDIA swore up and
4:30 down makes no difference makes no difference now we don't know
4:33 if this is because it's gen 3 or if it's because it actually has all the pins but
4:40 what we do know is that our 650 ti
4:43 didn't go as far as our titan xp at the
4:47 same resolution i mean arguably this is a bit of an edge
4:50 case but um one can say the scenario is somewhat of
4:54 a stretch i think we're gonna have to go even
4:59 further straight to three meters
5:02 should we do it yolo
5:05 okay this is ridiculous i mean why would anyone need to no we need more table we
5:10 need more table you have to hold the monitor now this is what happens
5:15 in your relationship how many times do i have to say i'm not yelling at you i'm
5:18 yelling with you okay be honest with me though are we expecting this to work no common
5:24 it's on no artifacts or anything
5:28 this is crazy how's it doing though 120 FPS same as
5:32 before we're still getting the same frame rate
5:36 no weird anomalies three meters
5:40 that's like 10 feet for americans
5:45 add 30 or add 60.
5:49 do i really have to scream yolo okay
5:52 monitor over on the other side and then just hold the graphics card here
5:56 this is insane that's the last piece we have yeah 3.6
6:00 okay no one come through this door
6:06 no it's still working
6:12 no way wait
6:16 maybe that's all we got oh oh it's at postcode 40 now
6:20 same as last time eh same as last time okay hold on let's shut it down no let's
6:24 i'll do a quick reconnect of all the things okay hold on also keep in mind
6:27 that these are not powered so perhaps it's not even signal loss it's just
6:31 power loss oh you could be right
6:34 three two one blast off
6:38 no look at this
6:43 look at this 3.6 meters
6:47 you could literally have your graphics card
6:50 in another room okay hold on i gotta run for mark though
6:55 show me the 120 oh oh oh oh oh
6:59 no
7:03 no the FPS is going up though it's at 55 fp
7:08 86 25 14
7:12 30. no
7:17 oh wait no it's so borderline
7:25 oh it just teases me every time
7:29 welcome to my personal life oh okay well i think we've reached the
7:33 limit ultimately we failed when we tried to
7:36 yolo too hard but i still consider this a success
7:41 three meters of pci express extension
7:46 and we managed to get it running at a an equivalent to having it right in the
7:51 socket 120 FPS
7:56 so thanks to thermaltake for providing all these PCIe risers and thanks to
8:01 the uh slav for holding the graphics card how's that 85 degree GPU right
8:05 there i stay holding my hand against the hot
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