What are the system specs, specifically the CPU and where it has a decided GPU.

I own a E5530, a E6440 and an E6540, and have upgraded the CPUs on 2 of them, so I'm pretty familiar with this basic platform.

The E6540 was upgraded to a quad-core i7 and I haven't had any cooling issues at all.

The cpu is an i7 3720QM Quad Core

And the Graphics are Intel HD 4000 which is integrated and NVS 5200m which is dedicated

That's about the worst possible scenario out of the ones I imagined, but have you run a monitoring program to confirm that the clock speed was dropping when the system is under no or low load? And that the cores were a low or zero load during that time?

I had a similar problem (though not as bad - the fan would just run constantly and push hit air out) after upgrading the E6540 to a quad-core i7, and it only worked itself out when I updated the chipset drivers to the newest Intel (non-Dell) version. Then it disappeared.

But first load a monitoring program (I use the All CPU Meter gadget in Win10) to confirm that Speedstep and C-States are working right, and also confirm they are enabled in the System BIOS. Without those enabled at the BIOS and driver level, your CPU runs clock and voltage cranked all the time.

I checked and when nothing needy is running it will goes to low usage, but again; when playing games it just skyrockets and jumps to 99 celsius. Even my friend doesn't understand whats wrong and he is pretty smart with computers. The fan and everything is running and even on a flat surface I see no change in temperature. I recently laid  my laptop on my air conditioner blowing at 60 degrees Celsius while playing my game and even it wasn't able to do much, brought it from 95 to 87 when playing a game 

I think this is a pic of the copper dual-pipe heatsink that is supposed to ship with all quad-core i7's on the E6430:

And you made sure all the power-saving options (Speedstep, C-States, etc.) were set in the BIOS, right?

Also, did you monitoring program display core voltages?

I ask because even through the clock speed may be dropping down at idle, the core voltage could be staying high no matter what, which was my problem with a CPU upgrade. It seemed to work, but it was jacking the voltage at 100% for 4 cores, 24/7.

The usual stuff: Have you updated to the latest BIOS revision (A22 - April 26, 2018)? The BIOS can make a HUGE difference in CPU temps. Made absolutely sure the heatsink is flush to the CPU. There was an issue with the E6420 where there was sometimes a "gap" and you needed a thermal pad to make up the difference.

You said you bought this used, right? Well maybe the original owner had a dual-core in it, and then upgraded to quad-core, but kept the single-pipe cooling that shipped with the system? Back then, the CPUs ran pretty hot and believe Dell had 2 heatsinks, one for dual-core and a dual-pipe model specifically designed for quad-core 2 and 3-series processors.

See if you can have a look online to see the differences and then determine which one you have. If you have a single-pipe then I think that might be the problem.

Here's an old thread on the E6420, which is very similar to the problems I've seen with the Latitude 6-series from this era, and you should give it a read. It's not entirely E6430-specific, but it's the same basic design and same inherent issues.

https://www.dell.com/community/Laptops-General-Read-Only/GPU-Temperature-103C-on-Latitude-E6420/td-p/3831854

domcarminefilix, Did you find a solution to it? I'm having the same issue, please share if you did fix the problem.

i have the same issues but with even worse thermals it hovers around 70 85 while idle and 90 while minecraft and when the cpu is under any load the sound starts to distort and the laptop becomes unusable like even when playing arkam asylum i really need help too

In a nutshell:
Try to update the Intel integrated graphics card at: https://downloadcenter.intel.com/product/81499/Intel-HD-Graphics-4000

Long version:
After having the dell e6430 for >3 years and trying all kind of different solutions (updating drivers from dell support assist, applying the best thermal pastes etc), I could not get the temperature <60-65C at idle state, meaning that the laptop was loud and hot most of the time. At some point I had trouble starting up a graphical app and when I contacted the company sharing my msinfo32 file (laptop specs) they told me that the reason was an outdated driver for Intel integrated graphics. I updated the driver from https://downloadcenter.intel.com/product/81499/Intel-HD-Graphics-4000, which not only resolved my problem with the app but also dropped the idle temp of my laptop by 10-15C. This happened a few days ago, now when I am doing office work (min. 2 office programs + 3 firefox tabs) the laptop remains cool and the fan rarely works.

Couple weeks before this reply, my brother asked me to examine his E6430 for several problems including overheating and unexpected shutdowns.  He's no slouch when it comes to cleaning a laptop, thermal grease, and had already correctly performed normal servicing for such things.  Once I got some other problems squared away, last was the thermal issue.  An i7 with 8gig and a 480 SSD, Windows 10 custom, he said, and I confirmed that CoreTemp was reporting overall Celsius temps in the 70/80s sometimes 90's on startup but fairly quickly coming down to the mid 60's no lower.  He's a general office user.  Not a gamer but he likes having several browser connections open in Edge (with all the privacy and bloat issues corrected).  He reported that when in normal office program use, temps were constantly in the 70-80's even when doing nothing.  Said the fan was working and hot air was moving but never got better, topping out in the 90's.

Long story short (with Win10Pro without the bloat, drivers and updates current) and still no changes, I examined the radiator again and noticed the pads for the 2 regulators.  You could see the pads if you looked down the side of the radiator.  I couldn't believe it when noticing the thermal pads were either the wrong size originally (thin whites) or someone had replacement them incorrectly.  They seemed less than a mm thick per regulator.  I also noticed there was no indention from the edge of the regulators and these pads were slightly oversized for the tops of those regs.  Another thing was the pads were partially folded over in couple corners and should have been flattened by the surface of the regs but no, and with this fold over, you'd think the pads would be thick enough to reach the surface of the regs.  Nope. Even with this corner fold over, there was over a mm gap between the pads and the surface of the regs.  I had a new sheet of 1 and 2mm silicon Pads and after trying couple cuts for the twin regs from the 2mm sheet, I noticed that even though they seemed to be touching the regs surfaces, they didn't seem to be pressed enough against the regs to conduct heat well.  Testing showed only a slight decline in the temp average; nothing to brag about so I added another layer of 1 mil on top of the 2 mil and after some compression, reassembled the unit.  Testing showed that the former average of mid 60's was now in the mid 50's but that's not enough when considering the laptop was in a 20 degrees Celsius environment.  The final fix was in Bios.  Although the Bios was up-to-date, Speed-Step and C-States were both on, it was Turbo Boost causing the last problem.  Turning it off and tests showed idle was now in the mid to low 40's.  That's acceptable.  Testing for loaded temps showed the overall averages in the mid 50's to 70's but quickly returning to safe idle mid 40's with the fan acting normally.  An interesting set of discoveries.  After confirming that the cooler radiator assembly was perfectly level, no bowing; no bending, and that with the holding "springed screws' mounted correctly, the distance between the radiator and the surface of the regulators needs to be slightly more than 2 mil and that a 2-mil pad is not enough unless you bow the assembly to compensate.  Not going to attempt that.  The pads were measured with a micrometer, no mic'ing the gap, something difficult for me to accurately do.  I'd say the overall pad thickness accepted was about 2.2 mm.

All this is not to say that there's a gap problem with every E6430 but it's for sure, tuning off the Turbo-Boost is a good idea.

Hope this help in some way.