Tes4Mod:Hardware Analysis

As dated as Oblivion is, it can still bring very good systems to the ground. If you do not want your computer choking on it, first consider the types of specs you should have. Two users can have the same system specs and a similar number of mods, but with a certain group of mods installed, the two could have huge differences in average FPS and performance.

''The Breakdown - by component''

CPU (Processor)
This is the most important component when it comes to Oblivion, the bottle-necking component of most current systems. Oblivion was not written to take advantage of multiple cores, so if you need to save money get a fast single or dual core. A 3.0 GHz dual core is good enough to run almost any modded setup with reasonable performance. A 3.2GHz single core and 2.4GHz dual core can probably still run many setups with reasonable performance; however, keep in mind that the more pressure your CPU is under the greater the instability of your game. If your CPU overheats and forces the computer to restart or shut down while playing, reduce your setup. The reason why the CPU is so important is because of Oblivion's AI processing...performance. The mods that hit the CPU most heavily are mods that add AI packages and heavy scripting. (Most script-centric mods do not actually put too much pressure on your setup unless they are poorly designed or buggy. Hrmmmn's Oblivion Script Optimizer has the latter issue.) AI packages are attached to NPCs and scripts can be attached to almost any kind of object. Many mods that add new sounds often do so by attaching scripts to individual items. The pressure from those mods can add up from the sheer density of the script-attached objects in an area. NPCs are added by all kinds of mods, but overhauls, creature diversity mods and population increasing mods are the ones to be most careful about adding when CPU load is a concern. To reduce the pressure on your CPU, reduce the distance at which NPCs and objects are loaded in video settings (ESC menu), install spawn-reducing plugins, and keep the script-centric mods up-to-date. Read the sound card section (below) may be useful as well. 

Sound Card
This $25 or more investment can unload a lot of pressure off of your CPU, as long as it supports hardware acceleration. The sound card will then take on the bulk of the sound processing for the game. If you do not have a sound card, make sure to install the Quiet Feet MAX mod to reduce the sounds process. There are also some INI tweaks that are safe and can also help reduce the sounds that need to be processed during the game. 

GPU (Graphics/Video Card)
Unless your system is really dated or has integrated graphics, this is the easiest component to modify your setup for. If you have 256 MB of dedicated VRAM (...or less) refrain from installing high resolution textures packs. Installing optimized meshes patches for Vanilla Oblivion and mods (when available) should benefit any setup, but, for those that really need the reduced polygons, they can help tremendously. 512 MB is pushing it once you start talking about adding big texture packs such at QTP3. QTP3 Redimized should be fine as long as your setup does not also include many other texture packs and aesthetic overhauls (i.e., Better Cities.) One of the best things you can do to optimize your setup is to PyFFI-optimize your modded setup, especially the original meshes and mods with a lot of meshes (if they are not already PyFFI-ed.) After PyFFI-optimizing QTP3R, users with a setup that can actually run it without a problem should find that (by itself) it runs near to Vanilla Oblivion's performance. Also, remember to keep your eye on the latest drivers. (You can find links to the official ATI and NVIDIA driver downloads on the troubleshooting pages.) With the rate that GPUs are being developed these days, getting a card that can handle modded Oblivion should be as easy a finding a current video card with 512 MB of dedicated VRAM. (Dedicated VRAM is the spec listed on the GPU's online page or packaging. If you think your single video card has more than 1GB of VRAM and you did not spend at least $600 for it, you should probably check again.) Keep in mind, that the even best GPUs will not continue to put out amazing FPS with a fully modded setup that includes QTP3 and a visible when distant mod. This is not Fallout 3 or Crisis. 

RAM (Application Memory)
If you have at least 3GB of RAM on a 32-bit OS or 4GB of RAM on a 64-bit OS, RAM is not stopping you from playing modded Oblivion (for a few hours at least.) Eventually, a heavily modded setup will reach its RAM ceiling, about 1.8GB on a 32-bit OS and (after patching it with a special program) 3.8GB on a 64-bit OS. Once that happens, the game will crash. Once you figure out how long it takes your setup to reach that point (if ever) quite before it gets there. Oblivion does not have great memory management, so it is always worth while to throw in a buffer management mod or two on your setup. The two major utilities for this purpose are the OBSE plugin the Oblivion Stutter Remover (OSR) and the (regular) plugin mod Streamline. (See information on setting up the latter on this site. For OSR, find its latest thread and read the documentation if you feel a need to tweak it.) 

HDD (Hard Drive)
Sometimes this overlooked part of your system can have a big affect on performance. Everyone should defrag their HDDs regularly. It is especially important to defrag after installing and uninstalling large quantities of data (i.e., after installing Obivion or even large mods.) The other things to watch out for are firmware updates. Try to keep the drivers up to date for all of your components, not just your video card. Finally, if you can handle setting one (or get a system with one pre-configured) a RAID array can pay big dividends.

The Rest

All other hardware
Make sure it actually supports the various components above if you build a PC for yourself or decide to upgrade a part. You can always ask for recommendations and advice in the BethSoft Hardware and Software forum and other tech forums online. 

OS (Operating System)
If you are not running Windows XP or Windows 2000, there may be a few hoops to jump through, especially if you do not heed the "WinVista" and "Win7" users warnings. 64-bit is better if you want to be able to offer Oblivion more memory space. 

DirectX
You should have version 9.0c of DirectX installed. Earlier versions definitely do not include the 9.0c DLLs, but later versions that come with the new computers often seem to lack the required 9.0c DLLs as well. Trying to install this version again will not hurt.

See Also
System Requirements