Firstly I want to give a big thank you to all the helpful people on tom's hardware forums, who have been helping me out ever since i got my new computer. I always come to these forums whenever i have an issue with anything at all, and i can feel comfortable knowing that within a few hours, a lot of kind, computer-smart people will post a reply to help me out with my problem. Every time so far, my issues have been fixed or at the very least been brought a lot closer to being fixed, because of your efforts. So thanks
I've installed GTA IV recently on my computer, and installed the ICEnhancer mod, as well as the enhanced city textures mod. My frame rates for the most part hover around 45 - 50 sometimes going up to 60 at nighttime, but when i look towards the river where you can see the big city across the river or at other very specific points, my FPS drops to the low 30s and sometimes even goes to 26-28. I don't really understand why, as the game has both of the GTX 590 gpus at 96%-98% usage, and I don't think i have a bottleneck because my CPU is a core i7 2600k OC'ed to 3.8 ghz, and i have 8gb of RAM.
Now, I know i have the game modded to make it look quite a bit better, but i'm not sure if Icenhancer or the city textures mod actually make the game more demanding - should i be concerned about these frame rates?
Yes the mods make the system more demanding. Some mods are written in a way that some video cards just can not handle them properly. I read someone that had the same mods as you using a GTX 580/i7 and was getting frame rates in the single digits. Slideshow! Those mods look great btw.
The solution to your problem is to turn down shadows from very high to high.Your fps will increase by nearly 15-20
Your fps will go down even more when it rains in the game.The parts where the game lags is the dawn at 4-6 AM and in the evening at around 7 30PM.I asked the moderator on gta 4 forums and he said that the hardware to run the game at 60 fps is not available.He also said that when rockstar games benched the game they had dual gtx 470s and they got 30 fps which according to them is playable.Just lower shadows to high and you will get a constant 50+ fps