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Regular Contributor
szhosain
Posts: 36
Registered: ‎01-18-2012

Speedtest results different between a PC and a Mac?

Hi, all.

 

I am seeing a significant difference in speedtest.comcast.net performance between two computers: a Leno W500 running Windows 7 64-bit and a 18 month iMac running the latest Lion release.

 

Both are WiFi connected to a D-Link 655 router that connects to a Netgear WNDR4000 router that connects to the Zoom 5341J cable modem to Comcast.

 

Using Chrome, on the Lenovo, I consistently get near 34 to 35 Mbits/sec down and 4.7 to 4.9 Mbits/sec up. The numbers are similar to what I get from speedtest.net directly.

 

Using Chrome and Safari, on the iMac, I consistently get about 8 to 10Mbits/sec down (sometimes as low as 3 to 4 Mbits/sec) and 5.4 to 5.5 Mbits/sec up. These numbers are also similar to what I get from speedtest.net directly.

 

Thoughts and comments? Does something need to be tweaked on the iMac to improve its performance in this regard? Is something mis-set on its WiFi card perhaps?

 

Thanks for anything you might recommend.

Regular Contributor
szhosain
Posts: 36
Registered: ‎01-18-2012

Re: Speedtest results different between a PC and a Mac?

And, yes, I know it is somewhat silly to have both a D-Link and the Netgear in the path - it is just a question of location. The Netgear is near the cable modem to provide the routing function (and local computer near it that is hard-wired to the Ethernet port on the router) and the D-Link is near where the above-mentioned computers are located.

 

Now, if the resutls were lower for both the Lenovo and the iMac, I would look into simplifying things in the network. But the fact that the two are giving me very consistently different results means that something is not right with the iMac.

 

By the way, my son just tested his school Apple Macbook and it gets close to 30Mbits down and 5.5 Mbits/sec up on the same WiFi setup ... unlike the iMac.

 

 

Networking Expert
Baric
Posts: 24,238
Registered: ‎07-28-2003

Re: Speedtest results different between a PC and a Mac?

Is it possible the systems are connecting to the different routers wireless?  Both those models are wireless, do you have wireless on one disabled, or run two different wireless networks, or are they both on the same SSID? 

 

Assuming both systems are connected to the same router and nothing in the vicinity of the iMac is causing wireless interference (cordless phone, wireless remote, wireless keyboard or mouse, etc), then it might be a hardware or software issue on the iMac.  What model, exactly?  Are you running any security software, like a virus scanner or third party firewall?  What about CPU usage, is the system busy (ie. is something running in the backgroud)?  How is the hard drive on free space?

 

It might be interference, have you tried changing the wireless channel on the router(s)?

Regular Contributor
szhosain
Posts: 36
Registered: ‎01-18-2012

Re: Speedtest results different between a PC and a Mac?

Thanks, Baric.

 

Here is what I have seen so far with lots of testing. And I do have some additional info from the Apple web site that may have direct impact, so I will mention that shortly!

 

1. All systems are definitely on the same router - plus the symptoms are pretty much the same on the other router too!

 

2. The specific Apple is an 27" iMac purchased in Dec of 2009 - not that old - with Dual-Core 2 Duo intel and plenty of free main memory.

 

3. The Apple processor and system are not loaded at all - even freshly booted, it shows the same problem.

 

4. Hard drive is relatively open - no space problems there.

 

5. Tried channel changes to 1, 3, 6 and 11 - same outcome and no real change. So, I went back and reset the D-Link to "auto" ... which searches for and then finds the best available channel to use.

 

6. Tried changing the channel bandwidth from 20MHz to 40Mhz - same poor outcome.

 

7. I am not sure about a wireless keyboard or mouse issue, since I can't really turn those off to use the system conveniently, although I could try it without the mouse on.

 

8. No security or firewall software - jsut whatever the Mac OS has (we are running the latest 10.7.2 Lion version, with all updates done).

 

9. I tried booting into Windows 7 on the iMac to see if the latest set of drivers there would make a difference, but nope - same problems! Which means that it is probably a hardware issue - not drivers!

 

At the Apple site, there are a lot of complaints of WiFi on the latest iMac systems, particularly after an upgrade to Lion. In many cases, their performance amnd issues is far worse than the speed problem we are experiencing - they see lots of timeouts (although we have our share of those), errors and no connections at all.

 

Two of the solutions mentioned there have helped:

 

(a) Physically turning the iMac so that the back of the computer (with the plastic section where the Airport card antenna is located) faces the router, but this is too awkward to use. That brought the rate up to about 13 to 18 Mbits/sec.

 

(b) Deleting all "known" networks, changing the Location info, and re-starting from scratch. That also brought it up above 20Mbits/sec for a while, but it has degraded again.

 

It simply looks like the iMac has a very poor WiFi card/antenna design - since the case is entirely Aluminum, the only place where the WiFi antenna can be placed is behind the plastic on the logo in the back. This apparently makes it very sensitive to location and direction!

 

If I cannot get this fixed, I am going to have to simply move the computer to another location in my house where I can reach it with a hard-wired Ethernet connection to the same router. :smileysad: That should take care of things entirely, but I will test first before I lug the heavy desk around.

Web Page Expert
BethKatz
Posts: 6,167
Registered: ‎11-14-2006

Re: Speedtest results different between a PC and a Mac?


szhosain wrote:

.... 

If I cannot get this fixed, I am going to have to simply move the computer to another location in my house where I can reach it with a hard-wired Ethernet connection to the same router. :smileysad: That should take care of things entirely, but I will test first before I lug the heavy desk around.


You can get some pretty long Ethernet cables.

 

Is there a way to move the router or the iMac to get them closer together to test the physical WiFi properties temporarily? You mention "heavy desk". Is the router on the same floor as the iMac? When you tried the laptop, was it on the desk and near the iMac or was it near the router?

Regular Contributor
szhosain
Posts: 36
Registered: ‎01-18-2012

Re: Speedtest results different between a PC and a Mac?

[ Edited ]

Hi, Beth.


Thanks for the response!

 

BethKatz wrote:

 


You can get some pretty long Ethernet cables.


True! :smileyhappy:

 

It is just that my house is wired (inside the walls - had it done when we built) with Cat-5e Ethernet cable, so I have RJ-45 wall-jacks in most rooms, but unfortunately just not near where the iMac is currently placed!

 

Basically, I cannot add a cable from the closest jack to the iMac - it would have to cross some open floor areas and the tall opening to our family room. The WAF factor would be tough to overcome.

 

BethKatz wrote:


Is there a way to move the router or the iMac to get them closer together to test the physical WiFi properties temporarily? You mention "heavy desk". Is the router on the same floor as the iMac? When you tried the laptop, was it on the desk and near the iMac or was it near the router?


1. Router is on the same floor as the iMac - however, the back of the iMac faces away from it (this is likely the reason for the problem).

 

BTW, previously, I also got full 300 Mbits/sec (WiFi connection only, of course) from a old Dell PC on that same desk - using a D-Link PCIe WiFi card with a triple MINO antenna. That PC was replaced with an iMac.

 

2. When I tested, I put the laptop deliberately near the iMac (i.e., on the same desk) ... to ensure "similar" radio conditions as much as possible. So, "same distance" from router to either the laptop or the iMac.

 

3. Yes, I can move the iMac - in fact, that is what I meant by "test first". :smileyhappy: I will take it over to where the desk would need to be. I will connect it via Ethernet cable over there, so the need to use WiFi would be moot.

 

4. And, yes, the router could be moved near the iMac for testing purposes with a long Ethernet cable. But leaving it there would have the same "can't put cable to it permanently" issue. So, not a long term solution regardless.

 

I have also debated simply getting a WiFi Access Point set up as a repeater placed near the iMac to see if that does the trick - ZyXEL has a low-cost unit (their 3205, I think?) available at Amazon for about $35, as I recall.

 

Anyway, based on more reading at the Apple web site, this issue appears to be a fundamental problem with the iMac WiFi card/antenna design - these systems are apparently very sensitive to placement and orientation to the WiFi router/access point.

 

Perhaps the same antenna guy who worked on the iPhone 4 worked on the iMac WiFi antenna design! :smileysilly: I jest, I jest!

 

Z

Connection Expert
EG
Posts: 42,589
Registered: ‎12-24-2003

Re: Speedtest results different between a PC and a Mac?

Perhaps "powerline ethernet adapters" may help you ? Google for info.

Regular Contributor
szhosain
Posts: 36
Registered: ‎01-18-2012

Re: Speedtest results different between a PC and a Mac?

I did find those - they are a bit too expensive, I think(?) Might be easier to simply move the iMac or add a cheap access point repeater.

 

I will look into those again ... thanks!

 

Z

Networking Expert
Baric
Posts: 24,238
Registered: ‎07-28-2003

Re: Speedtest results different between a PC and a Mac?

I would buy a Mac compatible USB wireless adapter, disable the Airport in the iMac, and install/setup the new adapter and test the speed.  If faster, you've found your problem and have an installed solution.  If not, the problem is NOT iMac's Airport adapter and you need to look elsewhere.  Lots for sale out there:

 

Amazon search

 

I have no issues with the Airport adapters in my MacBook Pro's (two of them), but I don't have an iMac so I can't offer an opinion there.

Regular Contributor
szhosain
Posts: 36
Registered: ‎01-18-2012

Re: Speedtest results different between a PC and a Mac?

Good suggestion on the USB adapter. I will try that ... I wish the iMac had a PCMCIA slot though, since I have one of those lying around anyway. Oh, well.

 

Z