I overclocked my ram without adding voltage and my pc don't want to boot up
Folks can't really help you without a lot more information about your setup. Overclocked RAM requires a bunch of things:
■ Proper Speed
■ Proper DRAM voltage
■ Proper VCSIO voltage
■ Proper Primary Memory Timings
■ Proper Secondary and Tertiary Memory Timings
When overclocking memory, you usually start with an XMP setting that comes in the DRAM. Your motherboard reads some preconfigured settings from the DRAM chips and offer that as a choice in the BIOS. This will generally be a DRAM voltage and a set of primary timings that your DRAM is supposed to work with. The motherboard will then calculate and test out various secondary and tertiary timings that should work with your memory. I think most people would say that you should get your system stable at the max rated XMP settings first and then use that as a known basis for going faster. When things go haywire as you test faster settings, you can always come back to your last known good settings.
The process of going faster than the preconfigured XMP overclocking involves educated guesses for a DRAM voltage, VCSIO voltage and primary timings that will work. Within safe limits for your hardware, you can guess higher voltages than you will probably need, find some timings that will get you booted, do short stress test. If you pass, either try to go faster or try to trim down the voltages to lower levels so you aren't using more voltage than necessary. Eventually, when you think you have good settings, you want to do long stability tests with something that stresses the memory like RamTest or MemTest86 (I use both). I use PassMark's MemTest86 booted from a USB stick when I'm testing the edges of stability because this doesn't require a boot into Windows and thus doesn't run any risk of corrupting Windows. I let MemTest86 run overnight multiple times during the testing to assure DRAM stability.
VCSIO voltage is also important in DRAM overclocking. My motherboard automatically picked a value too high for that and my stability improved when I lowered it and ended up around 1.25V, but every situation is a little different.