Here's my system

Sapphire ATi Radeon HD 3870 PCI-E 512MB GDDR4
AMD Athlon x2 6000+ 3.0Ghz
Kingston DDR2/800 1GB PC6400 Non-ECC CL6 DIMM [x2]
MSI K9A2 Platinum AM2+ Phenom,790FX/SB 600
450W PSU
250GB SATA-II, 7200RPM, 8M, Caviar
Samsung 2032BW


In css i only get 130 fps on the stress test with all max 4x antialiasing and 8x anisotropic 1680x1050

In-game my fps sometimes drops to 45.
Drivers are updated:
Catalyst 8.6
AMD Dual Core timing fix
AMD Processor driver

I cant fix this problem i really need help

The Stress Test and the Online play are completely different. I too am able to easily get 150FPS in CSS on the Stress Test albiet a lower end card (HD2900Pro 1GB).

Unfortunately I do not play it much, more of a TF2 fan. But I would suggest heading over to http://www.steampowered.com and checking the CSS forums as I am sure there will be more people there who can help you.

Also check your rates. Sometimes they get messed up and cause lower FPS. Rememebr this as well, Source is a very CPU intensive engine and like the newer faster CPUs especially in the online games.

I was researching on the steampowered forums too and i still cant see whats the problem. My rates are :
cl_cmdrate 100
cl_updaterate 100
rate 30000

I've tried everything!

What's your fps_max set to? Also, rate should be 25000 not 30000

my fps_max is set to 0 and i also tried 25000 still no difference

If you're running anything newer than Windows 2000, get more RAM. 2 gigs minimum, 4 recommended (by me).

Well i have 2gb ram thats enough for xp

Most likely your cpu. I get 345 Fps on the stress test with the exact same settings on my pc. Try increasing Fps_max to 500 and turn down or disable AA but leave on af because the 3870's hurt bad when it comes to AA. Source is probablythe most CPU dependent game. By switching my 3700+ with 8800gts320 to an e6750 and with same card, my fps went from 100fps to 240. Plus you can notice a difference under 100 fps. Plus my ati card has much less micro-stuttering than my old 88.

you get 345 on that system? I get 300 with 2 ultras. strange

I wouldn't mind the very occasional drop to 45fps. this can be due to lag, too many people on screen at once, etc...

i guess since you're coming here the problem is more extensive though. just to make sure, you do have the latest drivers/direct x updates right? I've noticed (most recently in The Witcher) that certain driver releases sometimes cause a noticeable drop in FPS in specific titles.

Thats probably a lag it only happens when there are lot of people on screen

valvle games are mostly cpu limited, get a better one
I get around the same fps as you with a X2 3800+ ( same fps with both a HD2900XT and now with my 3870... )
so yeah.. cpu bound

CS:S does not work with SLI. So you are only really using one Ultra. Plus ATI supports Valve with highly optimized drivers for their games that support xfire but not SLI, hence the half-life logo on all their boxes. So all that would explain me having higher fps, but there could be other reasons, but those are the main ones.

Hmmmmm.....thats weird cuz a Guy posted a video on Youtube of him playing HL2 Lost Coast with 2 8800GTXs SLIed and at a res not capable by a single card.

Then again CSS and HL2 are different games so you neve know.

its the aa ati cards suck for aa turn that off and you should be good i get around 300 fps almost all the time on any server with my rig so its not your setup the psu your using seems a little small for the video card and everything else.

I will agree that the PSU seems too weak. The GDDR4 is known to use more power. But AA is not the main problem. I can run CSS and get great framerates with AA maxed same goes for TF2 and HL2. But come to think of it the PSU might be causing the GPU to stay at its lower clocks.

Well how can i see if the psu is the problem?

get a new psu and if it doesnt fix it return it i work retail people do it all the time get a cheap one from bestbuy if it improves performance either keep it or return and get a new one.

lol any other way?
I cant do that :S