Dell optiplex 960 > what is the fastest GPU

The dell 960 desktop is low profile so you will probably only be able to use an HD 7750 LP gpu. As to the 755 - if the PSU can handle it the 7770 is probably the best (though I might be slightly ATI biased as I've never used nVidia except the Quadro professional cards).

I am sure you seen this before, but for clarifications I will do it again.

THIS IS FOR Optiplex 755 Mini-tower

Not so many user know the limitations of Optiplex Mini Tower cases - this is not your typical small ATX case, it is BTX case (old models), and not all video cards can fit, so I will provide you all with small guide into Optiplex MT GPU upgrading.

THIS POST APPLICABLE TO MT (MINI TOWER) FORM FACTOR ONLY.

Unfortunately no card that is more than 7.5 inches long or 2 slots wide will PHYSICALLY FIT inside the case - it was found that only single bracket video card can fit due to BTX MOBO, where card internals facing upward towards PC internals, not ATX, where dual card design is blocking another PCI slot by facing downward.
If you prefer the card with beefier fan, then the length of the card must not exceed 7.5 inches, otherwise only "skinny" single bracket, single slot cards can physically fit.

Pictures below will prove my point.

View shows no room for dual bracket



Single bracket only, or you have to cut dual bracket in half



Here you can clearly see only single place for the bracket



Visual explanation



7.5 inches explained, also shown "obstacles"



This is the picture of actual "skinny" single slot video card (not sure which model)- perfect, "glove" fit.



So, I found 2 GDDR5 7750 cards and one DDR3 4GB (GDDR5 is better than GDDR3, even if GDD3 offers 2 GB RAM or more), which confirmed in reviews to fit Optiplex gx620, 745 and 755 cases (the difference between those models are different processors).

Skinny, flimsier in terms of construction, completely single slot XFX 7750 http://www.amazon.com/XFX-DisplayPort-PCI-Express-FX775AZNP4-FX-775A-ZNP4/dp/B007Z3T5JC

A bit beefier cooler, not as skinny, more durable in construction PowerColor AX7750 http://www.amazon.com/PowerColor-AX7750-1GBD5-DH-Video-Graphics/dp/B00775OC28/ref=sr_1_1?ie=UTF8&qid=1362783129&sr=8-1&keywords=AX7750+1GBD5-DH

If you need Video card for working with high resolutions, BUT NOT FOR GAMING, PowerColor AX7750 4GBK3-H Radeon HD 7750 4GB is DDR3 card with huge 4GB memory, but is is not as fast as DDR5 and loosing in games http://www.newegg.com/Product/Product.aspx?Item=N82E16814131486&Tpk=7750&IsVirtualParent=1
Here is review of this card http://news.softpedia.com/news/PowerColor-Launches-Single-Slot-Radeon-HD-7750-4-GB-Video-Card-292712.shtml so this one is not for gamers!

I cannot say which one of those 2 DDR5 is better, both are good and got less bad reviews related to structural build.
I saw recent recommendation regarding drivers "Changing to the just-released AMD catalyst 13.2 BETA driver improved performance noticeably in just about every game" posted 03/05/2013. So older drivers are worse, can not comment about the newer ones, so this part is take it or leave it.

Next will follow maximum possible upgrade, 7750 is weaker...

So far I found only 2 7770 video cards which will fit inside - PowerColor AX7770 http://www.newegg.com/Product/Product.aspx?Item=N82E16814131477

HIS H777FN1G Radeon HD 7770 very tight fit, almost touching heatsink http://www.newegg.com/Product/Product.aspx?Item=N82E16814187200

From NVIDIA I see SPARKLE 700025 (SX650TI1024KD) GeForce GTX 650 Ti http://www.newegg.com/Product/Product.aspx?Item=N82E16814187200

7750 cards do not require power supply upgrade, 650 TI and 7770 are.

There are so many options available here so I would just recommend one of the good one CORSAIR CX500M (modular), which has just enough power http://www.newegg.com/Product/Product.aspx?Item=N82E16817139050 Also, with modular you can get rid of extra cables, believe me there are a lot of them.
You need 500 watt at least, stronger is better depending on your money.

Next is more difficult Optiplex 960 Desktop

In addition to low profile situation for GPU, there is one more problem - PSU, the original is 255 watt and it is very proprietary, see for yourself



So, basically you are limited in GPU choice by PSU of 255 watt. Yes, you can use riser for full height short GPUs, but you can not use anything faster than 7750 (limited by PSU), and in this case, you don't need riser at all - Sapphire 7750 low profile http://www.newegg.com/Product/Product.aspx?Item=N82E16814202002&Tpk=Sapphire%207750%20low%20profile&IsVirtualParent=1

It has phony power requirements of 400 watt, but you have to take a look here http://accessories.dell.com/sna/productdetail.aspx?c=us&l=en&s=dhs&cs=19&sku=A6523076&mfgpid=192262
This card is tested by Dell for many Optiplex DT models with the same power supply of 255 watt (look under Compatibility).
Also, take a look at Newegg user review by TazarZero who stated:

Pros: I am pleased to share that this card works painlessly in an HP Slimline s3400f that came with a 165w psu!

Click to expand...

No, I would not recommend this, but your PSU is 255 watt, so you have nothing to worry here.

I think I covered it all, any more questions?