Thanks for the suggestion.
I ran some tests and used top to monitor my nginx server and apache backend server. During this whole test, i still had about 60mb free on my nginx server and 80mb free (85mb before test) on my apache backend server. I can clearly see that the free ram was slowly decreasing on the apache server as it was running. So i can see it working (aside from the new process spawns taking about 2.7% mem usage).

But why isnt it using up almost all the free ram?

here is my output:

#ab -n 30000 -c 50 http://xxx.xxx.xxx.xxx/index.html

This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 50.56.117.62 (be patient)
Completed 3000 requests
Completed 6000 requests
Completed 9000 requests
Completed 12000 requests
Completed 15000 requests
Completed 18000 requests
Completed 21000 requests
Completed 24000 requests
Completed 27000 requests
Completed 30000 requests
Finished 30000 requests


Server Software: nginx/1.0.5
Server Hostname: 50.56.117.62
Server Port: 80

Document Path: /index.html
Document Length: 423 bytes

Concurrency Level: 50
Time taken for tests: 45.253 seconds
Complete requests: 30000
Failed requests: 15000
(Connect: 0, Receive: 0, Length: 15000, Exceptions: 0)
Write errors: 0
Total transferred: 20655000 bytes
HTML transferred: 12675000 bytes
Requests per second: 662.94 [#/sec] (mean)
Time per request: 75.422 [ms] (mean)
Time per request: 1.508 [ms] (mean, across all concurrent requests)
Transfer rate: 445.73 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 13 151.9 1 9610
Processing: 1 61 206.3 38 7767
Waiting: 1 58 203.6 37 7767
Total: 1 73 254.0 40 9613

Percentage of the requests served within a certain time (ms)
50% 40
66% 40
75% 40
80% 40
90% 76
95% 280
98% 759
99% 761
100% 9613 (longest request)