I don't think the 3820 can even overclock because of its locked multiplier. For current Intel CPUs you need to have a k series CPU, which has an unlocked multiplier to do any real overclocking. Unless SB-E is different from regular Sandy Bridge and Ivy Bridge and actually remains stable by bumping up the BCLK, you're not going to be able to squeeze more performance out of that chip anyway.
Since you do not have a "K" model Core i7 Ivy Bridge CPU, the only thing you can do is to increase the BCLK frequency. However, everything is tied to the BCLK frequency like the PCI-e slot and USB ports.
The BCLK is set to 100MHz. Generally speaking, you can probably push to 105MHz, but the PCI-e slot and especially the USB ports are pretty sensitive to the BCLK frequency. Above a certain frequency and they may stop responding. Push it even a little too much and the USB ports can be permanently damaged.
To OP, you should be fine with moderate overclocking (< 4.6GHz). Your CPU liquid cooling should be able to handle the extra heat.
Warning! Overclocking can reduce CPU lifespan & also your motherboard & memory too. If you're not familiar with overclocking, you need to do some research first. There are a lot of guides out there. It's not something can be covered here. The "OC Tweaker" in UEFI Setup Utility especially "Load CPU EZ OC Settings" can help you overclock your processor. Remember, when overclock, heat output also increased. So, you need very good cooling. Not just CPU, VRM (voltage regulator) also need good cooling. If you only doing moderate overclocking (< 4.6GHz), the stock heatsink on the VRM should do just fine & the CPU liquid cooler should be able to handle the higher heat output from CPU. Always monitor temperature & make sure VCORE VID doesn't exceed 1.5V.