Ok, we recently got some of the new R52N cards and wanted to try them out. First, I tried one R52N card in a RB133 and another R52N in another RB133. I made on an AP, and one a client. It took me awhile to figure out why it could only do around 13 Mbps, but I finally came to the conclusion that it was CPU limited.

So I thought, Ok I'll try it out on RB433AH's. First I tried two 802.11a cards on version 3 RouterOS. When the cards were put into turbo mode, I was able to achieve 40 Mbps without the CPU usage being maxed. Then I upgraded to version 4 beta 4, and could only achieve around 34 Mbps with the 802.11a card and the R52n. One of the RB433AH's had it's CPU maxed at 100%. I have both RB433AH's in bridge mode. The one that had it's CPU maxed is connected to the internet through eth2. eth1, eth2, and wlan1 are all Bridged together on it. So I'm guessing because it's connected to the internet through eth2, it causes that RB433AH to work harder than the other one.

I was really surprised at these results and do not see how those boards at 680 MHz cannot do better. What is the R52N card for if it's maximum throughput cannot be obtained because of board limitations. It seems like version 4 is wayyy slower than version 3. I realize a RB600 might do a better job, but the 433AH is a fairly new board. Does anyone have any suggestions, or will the boards just not handle any more throughput than that?

(update)
Apparently one reason I'm having trouble with the CPU usage is because I'm using the btest tool and i'm testing to the RB433's. However, even testing from a computer to a computer, I am having difficulty getting very high speeds.

what packets (tcp/udp) did you send, where did you genereate/terminate that traffic?\

For 802.11a link you can check routing-test package on 3.x version, that basically is the same as beta, but without N support.

we do the same test with 2 - rb433ah and 2 - r52n cards, in 5.x GHz, link at 35km, and we have the same problem, when we make traffic udp, the cpu is ok, its low, but when we make tcp traffic, the cpu is 100%. we try to put epoip in bridge, is worst, so we try with wlan in station pseudobridge to put in bridge, its a little bit better, but the cpu at high traffic is still 100%. we try with rb600, the result was the same....anyoane has solve the problem? the signal is -65db.

Any solution on this have and RB433AH with 2 Atheros 11N. Cpu goes up 95%