LGA 1366 cpu upgrade

[haiambetterthanyou]

Hi all, I’ve inherited a dell t7500 workstation from 2012, I intend to upgrade the gpu to a 980ti but I’m not sure about the cpu. There are two quad core Xeon e5620 LGA 1366 processors which I ran through the bottlenecker, and they are bottle neckig my gpu by 25%.
I have an intel 5520 chipset which only has PCI-e 2.0 for my gpu which uses PCI-e 3.0. Which bottleneck should I address first (taking into account the fact that if I change the motherboard I have to change the cpu)?
Either way I will have to upgrade the cpu. Any ideas on what cpu I should upgrade to, or general guidance on where I should go with this?

Thanks

 

[pdpouyan98]

better go for new platform lga1366 is dead
tell me your budget to suggest something for you ( if you like )

 

[haiambetterthanyou]

£100 but even if there isn’t much for that budget it would be good to have something to save up for.