RAM slots / RAM problem

[medar]

Okay first of all my pc is is some old HP pavilion crap but I need it for school. Currently I have 3 ram sticks installed in the mobo which is 1.5GB (3x 512mb smh), but when I try to add another 512mb ram that is working it does not want to turn on. All Ram slots and RAMs are working perfectly they were tested. When i power on the PC with the 4x512mb rams there are 3 beeps I think and a red light. Please help if you can. 

[medar]

1 minute ago, highrusher said:

Okay first of all my pc is is some old HP pavilion crap but I need it for school. Currently I have 3 ram sticks installed in the mobo which is 1.5GB (3x 512mb smh), but when I try to add another 512mb ram that is working it does not want to turn on. All Ram slots and RAMs are working perfectly they were tested. When i power on the PC with the 4x512mb rams there are 3 beeps I think and a red light. Please help if you can. 

btw IDK if its HP pavilion tbh but it looks like this but only the specs are worse: Intel Core 2 Vpro is the cpu thats all I know 

[mahyar]

is your modo ddr2?

[keysbeast13]

could have that last slot of ram could have gone bad seen taht happen deffently with older towers

 

[medar]

2 hours ago, keysbeast13 said:

could have that last slot of ram could have gone bad seen taht happen deffently with older towers

 

It hasn't I tried putting the 3 rams in different order and it works

[medar]

2 hours ago, mahyar said:

is your modo ddr2?

yes

[mahyar]

can you try using 1 gig or 2 gig sticks 

[medar]

1 minute ago, mahyar said:

can you try using 1 gig or 2 gig sticks 

I don't have that much and tbh I don't want to spend any more money for this pc its very old. But still I would like to use the maximum out of it.

[mahyar]

you said  only one slot isnt working? or the stick isnt working?

btw ddr2 ram is cheap nowadays