Re RAM, have a look at:

https://www.vegascreativesoftware.info/us/forum/minimum-requirements-for-vegas-pro-16--113476/

...in which the first reply comment referred to the then published minimum system specs for VP16. Included was:

8 GB RAM minimum (16 GB recommended; 32 GB recommended for 4K)

What performance problem are you having? System looks okay to me. I used 8GB of ram for years. Create proxys or do a ram preview if particular clips call for it. For HD I think you'd be fine as is.

Your 4-core 2600K @ 3.4 ghz is about as fast as my older 6-core Xeons @ 4.0 ghz. They are fine with 1080p work but could not keep-up with 4K. The 4-core i7-3770 will not offer much improvement for the fuss, but I would upgrade to at least 16 GB and use a separate internal 400 MB/s or faster SSD or RAID0 for your source files. You could also add a separate target drive, but a 100 MB/s SATA is fine since it can only be written to as fast as the system renders... However, I would not spend too much on older technology because it can quickly add-up to the price of newer, faster tech...

For instance, last April I upgraded one Xeon to a 9900K, motherboard, VEGA 64 & 32GB DDR4 for $1350 in upgrade parts using the same cases & drives as my Xeons. The 9900K is 2X faster rendering intermediates and many times faster working with HEVC MP4, etc. due to the CPU's QSV combined with VEGA 64. Around Christmas I got a $1000 6-core i7-9750H gaming laptop with an internal GTX 2060 GPU, 16 GB, and room for (2) M.2 drives & (1) SSD drive. It is also faster than my Xeons by about 40% and many times faster working with HEVC MP4, etc. due to the CPU's QSV

Thanks for the information. Yes, I can see memory is definitely something I should upgrade having only 8GB. My 8GB is two 4GB sticks. Do you think I should add two more sticks, or completely replace the ones that are in there now?. Here's what the spec shows for memory support for the board. What would be the best memory to go with?

4 x DIMM, Max. 32GB, DDR3 2200(O.C.)/2133(O.C.)/1866(O.C.)/1600/1333/1066 MHz Non-ECC, Un-buffered Memory
Dual Channel Memory Architecture
Supports Intel® Extreme Memory Profile (XMP)
* Hyper DIMM support is subject to the physical characteristics of individual CPUs. 
* Refer to www.asus.com or user manual for the Memory QVL (Qualified Vendors Lists).
* Due to CPU behavior, DDR3 2200/2000/1800 MHz memory module will run at DDR3 2133/1866/1600 MHz frequency as default.

I've been hesitant to move to Win10 because I heard a lot of people told me they didn't like it. But now that support for 7 has just come to end, I guess that's where I have to go. Perhaps I'll start with those two upgrades, memory and O/S and see how things go. To the other poster, yes, I always close background running applications and have Vegas be the only major application running.

Windows 10 is a must, especially if you intend on eventually upgrading to Vegas 17, where it is required.

If your board supports it, you'd probably get better performance out of 2 16GB sticks to get 32GB, or 1 stick if you only want 16.

Eventually, when you go to upgrade, take a look at the Ryzen 3 CPUs. Lots of bang for the buck.

@fr0sty thank you for the input.. Wow I had not even considered going AMD.. Better choice than Intel these days? Which CPU and Board combo are the best bang for the buck with AMD?

Something to consider on the RAM upgrade. Your MB supports 4 slots as you mentioned, you currently have 2x4GB Dimms already populated as you also already mentioned. A more cost effective approach would be to add 2x8GB additional dimms to your existing memory which would put you at a 24GB total which is plenty. Later if you decide to go full out to your system max of 32GB, then you can get two more 2x8GB dimms. This way you're not just throwing away the 8GB you already have and in the end, you'll likely spend less going bu purchasing four 4x8GB than you would with 2x16GB dimms as previously suggested.

It's easy spending other folks money, with forum suggestions. The approach I'm suggesting above saves you money and gives you more options to evaluate in the step process of an upgrade.

Most 4 dimm slot Mother boards, typical the only limitation is that you purchase them in sets of 2 matching pair which also allows you to use the XMP support that your MB provides if they are a matching pair.

@Rednroll, yes that was my plan.I called G.Skill and the guy on the phone said they don't recommend mixing different size memory. But from everything I can see, I think I'd be fine adding this pair to my existing pair:

https://www.newegg.com/g-skill-16gb-240-pin-ddr3-sdram/p/N82E16820231568?Item=N82E16820231568 so I think that's what I"m doing to do. Same brand, same specs.

I'd say investment in DDR3 RAM is dead end as all modern CPUs will need DDR4. So I'd upgrade the system as i7-2600K does not support modern CPU instructions (AVX) that are used in encoders. Also, it has only 4 cores (8 threads) that is not too much for video editing.

Modern CPUs are way faster (especially multi-core) and have much better RAM/SATA/USB performance (no NVMe in your CPU).

Ryzens are usually good choice, however there is a caveat. If you are going to AMD CPU you will lose iGPU that is good addition for decoding. Especially in your case as you have AMD GPU so decoding is not available on the RX 580.

P.S. If you are on tight budget, just get another 8GB (2x4G) of DDR3 RAM. YOu do not need more for editing FullHD. I would not worry about mixing different RAM brands as usually well known manufacturers co-exists quite OK. G'Skill offered lifetime warranty that I used a couple of times already.

@fifonik, the thought crossed my mind that the system itself is outdated at nearly 9 years old. Now I don't know what to do.. I don't understand what you said in your last paragraph about the caveat, can you elaborate on that so I can understand? If I go the AMD route is there a particular mobo and cpu combination that you recommend?

All modern Intel CPU have integrates GPU (called iGPU) that can be used for accelerating some parts of video editing process (might be tricky as monitor should be connected to the iGPU). For example, the iGPU can accelerate video decoding so CPU will not be doing this job. This is really important when you working with 4K / high frame rate video as the decoding becoming resource expensive.

As per parts recommendation: I'm not PC builder. I'm only building PCs for my home so I have quite limited brand/model experience. Usually all well-known brands (ASUS, GigaByte, MSI) are good. I'm trying to avoid ASRock as I used to have some issues (to be honest, I used to have issues with all brands mentioned above, the difference is -- how easy these issues were rectified).

Last time I prefer MSI or GigaByte for MB/GPU (you can check what I'm using now in my signature). So, I'd choose again MSI motherboard on B450 chipset with 4xDDR4 sockets and Ryzen 3600 or 3700X. Note: B450 chiopset does not support PCI-E 4. x570 chipset supports it but MB with this chipset is way more expensive.

The tricky part is support of the CPU by MB. Some MB on B450 chipset does not supports Ryzen 3xxx from the box and require BIOS update. So you have to have some older AM4 socket CPU to do the update. Some manufacturers/models allow you to do the BIOS update without CPU at all (my MB can to this, cheaper MB such as MSI B450 PRO VDH cannot do this). Or you can ask AMD to send you CPU to do this, however this takes some time (they offered such service for free). Newer MB revisions works fine from the box. If you going to buy this combo -- double check that the MB supports Ryzen 3xxx without BIOS update or ask seller to update it for you.

I have a two monitor setup and both monitors are connected to the GPU card. I also have a HDTV that is infrequently used for another purpose. When you say that the monitor should be connected to the iGPU, you mean the HDMI port on the motherboard should be connected to a monitor to get the benefit of the iGPU? If I connect the TV to that port, will that be sufficient? I'm going to add 16GB of memory to my current setup, and upgrade to Windows 10 and see how far that gets me at this point. I really don't want to go through the hassle and expense of a new build.

@MikeLV

Your CPU has also a build in GPU, this one: Intel® HD Graphics 3000, not the best and fastest but if that does not showup in Options/Preferences/ Video, it helped me to allow it in the BIOS as a build-in graphics.

Yes, I'm actually messing with that now. I enabled it in the BIOS, but now Windows is showing 6 displays; I only have actually 3. (and no, it doesn't show up in the video preferences, only the AMD video card does)

Yes, one monitor should be connected to the HDMI port that is on MB. I believe connecting TV to the port will do the trick (the iGPU shoul be enabled in BIOS as already mentioned). Also, you will need to install Intel GPU drivers (windows might install something automatically, but I'd install driver from Intel).

After that you should have two GPU options in VP preferences.

Yes, I'm actually messing with that now. I enabled it in the BIOS, but now Windows is showing 6 displays; I only have actually 3. (and no, it doesn't show up in the video preferences, only the AMD video card does)

I think you first have to upgrade to Windows 10

If you choose to build an AMD system, choose the x570 chipset for some future upgradeability since it supports PCIe 4.0, the fast 3950X processor, etc. Then, you could start-out with the affordable 3700X for $300 & upgrade to the 3950X (currently $750) when the price drops. The 3700X is as fast as my Intel 9900K is many apps although it won't be as fast in Vegas due to Vegas' older code that benefits from the 9900K's near 5.0 ghz overclock & built-in Quick Sync Video (QSV)… Of course you could choose the faster 3900X for $500 or 3950X for $750 which will last you a lot longer before you will feel the need to upgrade...

Like you, I was using 9+ year-old systems for video editing because Intel was slow to make improvements at the upper end until AMD released Threadripper to compete. Last April I chose the 9900K over Threadripper because I need fast single core performance for an older legacy app. However, today I would choose the 3950X over both of those because it has more cores AND they are clocked pretty fast... Handbrake performance on the 3950X is really fast...

I may not be AMD's biggest fan in the GPU world, but since Ryzen I have been in love with their CPUs.

I went ahead and ordered 16 more gigabytes of memory. Upgraded the machine to Windows 10 last night without a hitch. It's quite different from version 7, but I'm sure I'll get my head around it in time.

Question about the RX 590 video card. Windows 10 detected it and installed the driver as I can see it in the device manager. Does this mean I don't need to download the Radeon software package from the AMD website? I don't want to install anything I don't have to to keep things running smoothly.

@MikeLV

"Does this mean I don't need to download the Radeon software package from the AMD website?"

So far, I'm using the driver delivered by Microsoft with Windows 10 and haven't felt the need to download an AMD driver for my RX480. I have Windows 10 in-place upgrades as well as out-of-the-box installations. The in-place upgrades allow my scanner and some very old versions of Photoshop to work where a clean Windows 10 installation doesn't.

@fifonik said:

"All modern Intel CPU have integrates GPU (called iGPU) that can be used for accelerating some parts of video editing process..."

Intel HEDT processors (core i9-10900x, etc) generally don't have video adapters on board. One could argue that they are not that modern in view of innovations from AMD, but hey!

I'm eleven months from my next system upgrade and I've made a chastity vow not to buy a processor with a video adapter on-die. I'll use the power going to the processor socket for CPU cores.

@john_dennis Sure, you are precisely correct. I have to change 'All modern' to 'almost all modern', 'most modern' ' :)